Raj Thesis 2003

TEST ROOM DEVELOPMENT FOR BULK MILK COOLER

By

Solanki Rajkumar D.(090370721001)

Prof. Avdhoot N. JejurkarM.E (Mechanical)Assistant Professor

A Thesis Submitted toGujarat Technological University

in Partial Fulfillment of the Requirements forthe Degree of Master of Engineering

in Thermal Engineering

June 2011

DEPARTMENT OF MECHANICAL ENGINEERINGPARUL INSTITUTE OF ENGINEERING AND TECHNOLOGY

VADODARA-391 760

i

CERTIFICATE

This is to certify that research work embodied in this thesis entitled “TEST ROOM DEVELOPMENT

FOR BULK MILK COOLER” was carried out by Mr. Solanki Rajkumar D. (090370721001) at Parul

Institute of Engineering & Technology (21) for partial fulfillment of M.E. degree to be awarded by

Gujarat Technological University. This research work has been carried out under my supervision and

is to my satisfaction.

Date:

Place:

Supervisor Principal

Prof. A. N. Jejurkar Dr. Vilin P. Parekh

Seal of Institute

ii

iii

COMPLIANCE CERTIFICATE

This is to certify that research work embodied in this thesis entitled “TEST ROOM

DEVELOPMENT FOR BULK MILK COOLER” was carried out by Mr.Solanki Rajkumar

D. (090370721001) at Parul Institute of Engineering & Technology (37) for partial

fulfillment of M.E. degree to be awarded by Gujarat Technological University. He has

complied with the comments given by the Mid Semester Thesis Reviewer to my satisfaction.

Date:

Place:

Guide

Solanki Rajkumar D. Prof. A. N. Jejurkar

PAPER PUBLICATION CERTIFICATE

This is to certify that research work embodied in this thesis entitled “TEST ROOM DEVELOPMENT

FOR BULK MILK COOLER”, out by Mr. Solanki Rajkumar D. (090370721001) at Parul Institute of

Engineering & Technology (37) for partial fulfillment of M.E. degree to be awarded by Gujarat

Technological University, has been accepted for publication by the Second National Conference on

Emerging Vistas of Technology in 21st Century at Parul Institute of Engineering & Technology during

4-5 December 2010.

Guide

Solanki Rajkumar D. Prof. A. N. Jejurkar

Principal

Dr. Vilin P. Parekh

Seal of Institute

iv

THESIS APPROVAL

This is to certify that research work embodied in this entitled “TEST ROOM DEVELOPMENT FOR

BULK MILK COOLER” was carried out by Mr. Solanki Rajkumar D. (090370721001) at Parul

Institute of Engineering & Technology (37) is approved for award of the degree of Thermal

Engineering by Gujarat Technological University.

Date:

Place:

Examiner(s):

( ) ( ) ( )

v

DECLARATION OF ORIGINALITY

I hereby certify that I am the sole author of this thesis and that neither any part of this thesis nor the

whole of the thesis has been submitted for a degree to any other University or Institution.

I certify that, to the best of my knowledge, my thesis does not infringe upon anyone’s copyright nor

violate any proprietary rights and that any ideas, techniques, quotations, or any other material from

the work of other people included in my thesis, published or otherwise, are fully acknowledged in

accordance with the standard referencing practices.

I declare that this is a true copy of my thesis, including any final revisions, as approved by my thesis

review committee.

Date:

Place:

Solanki Rajkumar D.

(090370721001)

Verified

Supervisor

Prof. A. N. Jejurkar

vi

ACKNOWLEDGEMENT

First of all, I am indebted to Parul Institute of Engineering and Technology for giving me all the

utility that I needs towards the completion of this project.

With great pleasure I wish to express my deep gratitude to Prof. K. B. K. Lamba, (Head of

Department, Mechanical Engineering, Parul Institute of Engineering & Technology, Vadodara) for his

keen interest, constant encouragement and valuable guidance for this work.

I would like to express my deepest appreciation and gratitude to my project guide, Prof. A N

JEJURKAR, Professor, Mechanical Engineering Department, PIET for his guidance, patience for

giving advises and supports throughout the progress of this project.

With deep sense of honor and gratitude, we acknowledge our obligation to Mr. J. P. GOPAL,

Managing Director IDMCL, Mr. K. U. MANGLANI, General Manager IDMCL and Mr. H. R. Patel,

H. R. Manager IDMCL for their immense co-operation, valuable suggestions and encouragement for \

this project. We take precious opportunity to express our gratitude and sincere regards to Mr. Ankit

Gupta, Mr. Saurabh Vyas, Mr. Devendra Gupta, Mr. Vinay Nayak, Mr. N. H. Patel, Mr. Hemant

Kumar, Mr. Kuldeep Sishodhia, Mr. Sourabh Mishra and Mr. Ashok Nangal for their guidance, co-

operation, valuable and constant inspiration during entire period of our training. We are highly

indebted to them for their constant encouragement and able guidance during our training. We also

highly appreciate the co-operation of skilled technical staff of the plant and thank them who all helped

out in my project.

Not forget to my family members for their support, advises and motivation.

Solanki Rajkumar D.

(090370721001)

vii

TABLE OF CONTENTS

Sr. No. Contents Page No.

Title Page i

Certificate ii

Industrial Certificate iii

Compliance Certificate iv

Paper Publication Certificate iv

Thesis Approval v

Declaration of Originality vi

Acknowledgement vii

Table of Contents viii

List of Tables xiii

List of Figures xiv

Abstract xvi

1 Introduction 1

1.1 Introduction 1

1.2 Installation Objective Behind Bulk Milk Cooler 2

1.3 Advantage using Bulk Milk Cooler 3

1.4 Types of Bulk Milk Cooler 3

1.4.1 Open Type Bulk Milk Cooler 3

1.4.2 Closed Type Bulk Milk Cooler 4

2 Literature Survey 5

2.1 Bulk Milk Cooler 5

2.2 Performance of Bulk Milk Cooler 6

2.3 ISO 5780:1983 Test Set Up for Bulk Milk Cooler 9

2.3.1 Test Set Up for Bulk Milk Cooler 9

2.3.2 Specification for Prefabricated Wall 10

2.4 Heat Load Design 11

2.5 Variable Chiller Flow Pumping 11

2.6 Piping Design 12

2.7 HVAC Control 14

viii

3 Air Conditioning System 15

3.1 What is Air Conditioning 15

3.2 Air Conditioning Systems Classification 15

3.3 Central Air Conditioning Systems 15

3.3.1 Central Air Conditioning System Components 15

3.3.2 Advantage of Central Air Conditioning System 16

3.3.3 Disadvantage of Central Air Conditioning System 16

3.4 Decentralized Systems 16

3.4.1 Advantage of Decentralized Air Conditioning System 17

3.4.2 Disadvantage of Decentralized Air Conditioning System 17

3.5 Applied Psychometrics 17

3.6 Description of Terms, Process and Factors 18

3.6.1 Sensible Heat Factor 18

3.6.2 Room Sensible Heat Factor 18

3.6.3 Effective Sensible Heat Factor (ESHF) 19

3.6.4 Air Quantities using ESHF, ADP, and BF 20

4 Heat Load Calculation 21

4.1 Summer Season 23

4.1.1 Inside Design Condition 23

4.1.2 Outside Design Condition 23

4.2 Sensible Heat 23

4.2.1 Solar Heat Gain through Glass 23

4.2.2 Heat Gain through Building Structure 24

4.2.3 Transmission Heat Gain except Walls 25

4.2.4 Infiltration and Ventilation Heat 26

4.2.5 Internal Heat 27

4.3 Latent Heat 28

4.3.1 People 28

4.3.2 Outside Air 28

4.4 Outside Air Heat 29

4.5 Apparatus Dew Point and Air Quantity 29

4.6 Prediction of Heat Load 30ix

5 Chiller Plant Design 31

5.1 Chiller Basics 31

5.2 Chiller Arrangement 31

5.2.1 Parallel Chiller System 31

5.2.2 Series Chiller System 32

5.3 Piping Basis 33

5.3.1 Open Loop Piping System 33

5.3.2 Closed Loop Piping System 33

5.3.3 Reverse Return Vs Direct Return Piping 33

5.4 Types of Piping System 35

5.4.1 Two pipe system 35

5.4.2 Three Pipe System 35

5.4.3 Four Pipe System 35

5.5 Flow Calculation 36

5.6 Types of Heat Exchangers 39

5.6.1 Shell and Tube Heat Exchanger 39

5.6.2 Plate Type Heat Exchanger 43

5.7 Selection Criteria of Heat Exchanger 43

5.8 Types of Chiller Compressors 45

5.9 Centrifugal Pump 49

5.10 Flow Control System 52

5.11 Selected Equipment 54

6 Test Room Layout 55

6.1 Cooling Process 55

6.2 Heating Process 55

6.3 Bulk Milk Cooler Test 55

6.4 Bill of Quantities 57

7 Performance of Chiller Heat Exchanger 59

7.1 Heat Transfer and Pressure Drop Calculation 59

7.2 Stepwise Performance Analysis 61

x

7.2.1 Required Heat Duties 61

7.2.2 Sizing of Heat Exchanger 61

7.2.3 Heat Transfer Analysis 62

7.2.4 Pressure Drop Analysis 65

7.3 Data Analysis of Thermal Heat Exchanger for Chiller Flow 67

7.3.1 Heat Transfer Trend for Chiller Flow 67

8 Bulk Milk Cooler Test 68

8.1 10KL Closed Type Bulk Milk Cooler Test 68

8.1.1 Room Temperature and Chiller Test 69

8.1.2 Bulk Milk Cooler Test 70

8.1.3 Calculation for Heat Remove from Condenser 70

8.1.4 Total Room Heat Load 71


8.2.1 Room Temperature and Chiller Result 73

8.2.2 Bulk Milk Cooler Test Result 74




8.3.1 Room Temperature and Chiller Result 76

8.3.2 Bulk Milk Cooler Test Result 77



9 Result and Discussion 79

9.1 10KL Bulk Milk Cooler 79

9.1.1 Compare Actual Chiller Flow and Required Chiller Flow 79

9.1.2 Average Room Temperature Trend 80

9.1.3 Predictable and Experimental Chiller Flow Trend 80




9.1.3 Predictable and Experimental Chiller Flow Trend 82

xi


9.3.1 Total Room Load and Chiller Flow Required 83



10 Conclusion 85

References 86

Appendix – A Heat Transfer Correlation for Plate Heat Exchanger 88

xii

LIST OF TABLES


2.1 Performance of Bulk Milk Cooler 7

2.2 Characteristic of Cooling Tank 8

2.3Comparison of Various Refrigerant used in 5000L Bulk Milk

Cooler8

4.1 Outside Design Temperature 23

4.2 Ventilation Standard 26

4.3 Internal Heat from Person for Various Activities 27

4.4 Load Prediction for Summer and Winter Data 30

5.1 Pipe Size for Required Flow Rate 36

5.2 Standard Steel Pipe Data 38

6.1 Bill of Quantities 58

7.1 Plate Heat Exchanger Data Sheet 59

7.2 Construction Data for Plate Heat Exchanger 60

7.3 Chiller Heat Transfer Analysis 67

8.1 Chiller and Room Temperature Test for 10KL Bulk Milk Cooler 69

8.2 10KL Bulk Milk Cooler \Test 70

8.3 Total Room Load for 10KL Bulk Milk Cooler 71







9.1 Compare Chiller Flow Rate for 10KL BMC 79



xiii

LIST OF FIGURES


1.1 Typical Open Type Bulk Milk Cooler 3

1.2 Typical Closed Type Bulk Milk Cooler 4

2.1 Two Piping System In Chiller Arrangement 12

3.1 Sensible Heat Factor Lines 19

4.1 Top View of Test Room 22

5.1 Parallel Flow Chiller 32

5.2 Series Flow Chiller 33

5.3 Reversed Return Piping 34

5.4 Direct Returns Piping 34

5.5 Friction Loss Chart for 40 Schedule Steel Pipe 37

5.6 Counter path in shell and tube heat exchanger 40

5.7U- Tube Shell and Tube Heat Exchanger with Removable Bundle

Assembly and Cast “K” Pattern Flanged Head41

5.8U-Tube Tank Heater with Removable Bundle Assembly and Cast Bonn

Head41

5.9U-Tube Tank Suction Heater with Removable Bundle Assembly and

Cast Flanged Head41

5.10Straight-Tube Floating Tube sheet Shell-and-Tube Heat Exchanger with

Removable Bundle Assembly and Fabricated Channel Heads42

5.11 Flow Path of Gasket Plate Heat Exchanger 43

5.12 Pump Efficiency Curve 50

5.13 Pump Pressure Curve for Parallel Arrangement 51

5.14 Pump Pressure Curve for Series Arrangement 51

5.15 Three Way Bypass and Mixing Valve 52

6.1 Test Room Layout 56

7.1 Dimension View of Plate Heat Exchanger 60

8.1 10KL Bulk Milk Cooler Set Up 68

8.2 Chiller Arrangement 69

8.3 5KL Bulk Milk Cooler Set Up 72

9.1 Average Room Temperature Trend for 10KL BMC 80

xiv

9.2 Chiller Flow Trend for 10KL 80





xv

ABSTRACT

Bulk milk cooling tank works as an important tool in maintaining the cold chain of milk

between the producers of it at rural area to the processing of it at main dairy plant. It provides

the cooling and holding milk at a cold temperature until it can be picked up by a milk hauler.

For this reason the bulk milk cooling tanks acts as a boon to the dairy industry. Present work

concerned to developed test facility for bulk milk cooler because of variation of ambient

condition affect the performance of bulk milk cooler. Test room is suitable for testing bulk

milk cooler up to maximum capacity under all condition specified in ISO 1983:5708 as far as

cooling test are concerned, the room temperature can be set within the range of 15°C to 50°C

with stability of 0.2°C. For this calculation of heat load and choosing cooling system element

such as evaporator, compressor, condenser for designing test room. Transmission heat,

Infiltration heat, product heat, heat of other sources and unknown and unexpected heat which

is component of heat load are calculated and designed chiller water arrangement based on

heat load calculation. Based on hot and cold water arrangement for different ambient

temperature obtained by controlling three way control valve that install in the system, three

way control valve set as per different type of bulk milk cooler equipment load and room load

for summer and winter weather data and also include one pipe arrangement for getting water

temperature set at 35˚C in bulk milk cooler and cool to 4˚C .After installation of system then

testing different type of bulk milk cooler for different ambient condition .For testing

particular bulk milk cooler set the chiller flow as per calculated design load and compare this

chiller flow with required experiment load to achieve uniform temperature of room and

dispatch the customer as per the said ambient condition. Thesis includes 10KL, 5KL and 2KL

bulk milk cooler test with maintain ambient condition.

xvi

CHAPTER 1: INTRODUCTION

1.1 INTRODUCTION [B5]:

As per the latest Draft Codex International Code of Hygienic Practice for Milk and Milk

Products from Codex Secretariat, if the milk is not processed within two hours of milking, it

is required to be cooled to a temperature below 4oC. Bulk milk cooling tank works as an

important tool in maintaining the cold chain of milk between the producers of it at rural area

to the processing of it at main dairy plant. It provides the cooling and holding milk at a cold

temperature until it can be picked up by a milk hauler. For this reason the bulk milk cooling

tanks acts as a boon to the dairy industry. Thus, the present scenario of collection system of

milk is chilling the milk immediately after milking by Bulk Milk Cooling Tanks. The usage

of such tanks has become popular in the recent past because it not only has helped in

increasing the shelf-life of milk but also provided systematic and simple way of the

procurement of milk. Also ensures procurement of more milk by covering untapped rural

areas for milk collection, where transportation facilities are scarce by providing only one time

transportation in a day and storing the milk of another milking in it.

Bulk milk cooling unit is used to cool raw milk at the village level co-operative milk societies

from the ambient temperature to 4 degree Celsius in conformity to specified ISO standard.

The cooling tank is used for cooling the milk immediately after milking to conserve quality

of milk and check growth of micro-organisms. It is intended for daily collection of milk. It is

a hygienic container built to sanitary standards, which besides cooling also serves as buffer

storage prior to transfer of milk for onward transportation and further processing.

The agitator provided in the cooling tank works intermittently and at a very gentle speed to

avoid damage to the milk fat globules.

The best alternative to present collection system of milk is cooling of milk immediately after

milking by bulk cooling tanks. The usage of such tanks has become popular in the recent past

because it not only helps in increasing the shelf life of milk but also provides a systematic

and simple way, to ensure procurement of more milk by covering untapped areas for milk

procurement.

Refrigeration plays a very vital role in dairy industry as milk and milk products are highly

susceptible to bacteria growth in very short time. Fresh milk does not form any bacteria for 1

the first 40 minutes, after that bacterium multiplies every 20 minutes in unprocessed milk. So

the quality of collected milk is preserved by cooling it as quickly as possible to below 4 °C at

milk collection centers with the help of Milk Coolers before dispatching it daily in insulated

tanks to big plant for further processing. Production of milk in India is very widely scattered

in the rural areas and at vast distances from the places of high consumption in the urban

areas. Dairy Farming as such is not a professional occupation but part of the overall

agriculture operation. The hygienic conditions and environment of milk production in the

rural area are still not up the desired standards. High ambient temperature throughout the year

in a tropical country like India is an additional disadvantage since the bacterial growth is very

rapid if the temp of milk is not brought down immediately after the production. It is very

essential to cool the milk immediately after milking to maintain the quality of milk as final

transporting to processing plant may take 8 hours or more from the time of milking. In fact

the chilling of milk at or near the production centers is the most important factor which has

influenced the growth of milk industry. The chilling of milk to about 4 °C or less is done to

check the growth of bacteria and preserve the quality as produced, until it is subjected to

pasteurization process. This is done at collection centers using Instant Milk Chilling Units

and Bulk Milk Coolers.

A milk cooling tank as a bulk tank or milk cooler, consist of an inner and an outer tank, both

made of high quality stainless steel. For a direct expansion tank, attach to inner tank is a

system of plates and pipes through which refrigerant fluid gas flows. The refrigerant

withdrawn heat from the tanks content (milk in this case). Direct expansion milk cooling tank

come with set of condensing unit which circulate the refrigerant and convey the withdrawn

heat to air.

1.2 OBJECTIVE BEHIND BULK MILK COOLER INSTALLATION:

1. Enhance and maintain quality of milk to avoid economic losses to farmers because of

spoilage/sour age.

2. To produce quality products for export and domestic requirements.

3. To reduce cost by regulating transportation of the milk on alternative days and also

through reduction in expenditure on purchase and maintenance of cans.

4. Flexibility in milk collection time resulting in increase in volume of milk collected at

the centers.

5. Farmers to get better returns for quality of milk.

2

6. Energy saving by avoiding chilling at the main dairy

1.3 ADVANTAGE USING BULK MILK COOLER:

1. Compact package unit simple to operate,

2. Power savings, almost trouble free running just like a large domestic refrigerator

3. Milk gets immediately cooled when poured progressively (Cooling Curve)

4. Only to be run during reception hours' and not a three shift operation

5. Can be easily relocated to other potential areas, being a package unit

1.4 TYPES OF BULK MILK COOLER:

1.4.1 Open Type Bulk Milk Cooler:

Figure 1.1: Typical Open Type Bulk Milk Cooler [B5]

It is available in the capacity ranges of 500L, 1000L, 2000L & 3000L, 5000L. Following are

the features of this type of cooler.

Features:

1. Available in horizontal rectangular/vertical circular configuration.

2. Designed as per ISO standards

3. Top cover is openable for direct tipping of milk.

4. Available in single phase as well as three phase electric supply.

5. Cleaning done manually with tank cleaning brush.

3

6. One agitator and one condensing unit up to capacity 1000L and two condensing units

for cap: 2000L and above.

7. Best option for small, remote societies

8. Low initial investment and operating cost

1.4.2 Closed Type Bulk Milk Cooler:

Figure 1.2: Typical Closed Type Bulk Milk Cooler [B5]

It is available in the capacity ranges of 3000L, 4000L, and 5000L. Following are the features

of this type of cooler.

Features:

1. Available in horizontal cylindrical configuration.

2. Designed as per ISO standards

3. Pump feed system for milk loading

4. Available in three phase electric supply.

5. Cleaning done using spray ball.

6. One agitator and two condensing units for all capacity.

7. Best option for large societies.

8. High initial investment and low operating cost.

4

CHAPTER 2: LITERATURE SURVEY

2.1 BULK MILK COOLER [P1]:

When refrigeration first arrived (the 19th century) the equipment was initially used to cool

cans of milk, which were filled by hand milking. These cans were placed into a cooled water

bath to remove heat and keep them cool until they were able to be transported to a collection

facility. As more automated methods were developed for harvesting milk, hand milking was

replaced and, as a result, the milk can was replaced by bulk milk cooler. 'Ice banks' were the

first type of bulk milk cooler. This was a double wall vessel with evaporator coils and water

located between the walls at the bottom and sides of the tank. A small refrigeration

compressor was used to remove heat from the evaporator coils. Ice eventually builds up

around the coils, until it reaches a thickness of about three inches surrounding each pipe, and

the cooling system shuts off. When the milking operation starts, only the milk agitator and

the water circulation pump, which flows water across the ice and the steel walls of the tank,

are needed to reduce the incoming milk to a temperature below 40 degrees.

This cooling method worked well for smaller dairies, however was fairly inefficient and was

unable to meet the increasingly higher cooling demand of larger milking parlors. In the mid

1950's direct expansion refrigeration was first applied directly to the bulk milk cooler. This

type of cooling utilizes an evaporator built directly into the inner wall of the storage tank to

remove heat from the milk. Direct expansion is able to cool milk at a much faster rate than

early ice bank type coolers and is still the primary method for bulk tank cooling today on

small to medium sized operations.

Another device which has contributed significantly to milk quality is the plate heat exchanger

(PHE). This device utilizes a number of specially designed stainless steel plates with small

spaces between them. Milk is passed between every other set of plates with water being

passed between the balances of the plates to remove heat from the milk. This method of

cooling can remove large amounts of heat from the milk in a very short time, thus drastically

slowing bacteria growth and thereby improving milk quality. Ground water is the most

common source of cooling medium for this device. Dairy cows consume approximately 3

gallons of water for every gallon of milk production and prefer to drink slightly warm water

as opposed to cold ground water. For this reason, PHE's can result in drastically improved

milk quality, reduced operating costs for the dairymen by reducing the refrigeration load on

5

his bulk milk cooler, and increased milk production by supplying the cows with a source of

fresh warm water.

Plate heat exchangers have also evolved as a result of the increase of dairy farm herd sizes in

the US. As a dairyman increases the size of his herd, he must also increase the capacity of his

milking parlor in order to harvest the additional milk. This increase in parlor sizes has

resulted in tremendous increases in milk throughput and cooling demand. Today's larger

farms produce milk at a rate which directs expansion refrigeration systems on bulk milk

coolers cannot cool in a timely manner. PHE's are typically utilized in this instance to rapidly

cool the milk to the desired temperature (or close to it) before it reaches the bulk milk tank.

Typically, ground water is still utilized to provide some initial cooling to bring the milk to

between 55 and 70 °F (21 °C). A second (and sometimes third) section of the PHE is added to

remove the remaining heat with a mixture of chilled pure water and propylene glycol. These

chiller systems can be made to incorporate large evaporator surface areas and high chilled

water flow rates to cool high flow rates of milk.

2.2 PERFORMANCE OF BULK MILK COOLER [P1, P2, B5]:

Direct expansion systems are the most common choice in farm milk cooling systems. In these

systems, the evaporator plates are incorporated in the lower portion of the storage tank, in

direct contact with the milk. Milk cooling takes place within the tank and one or more

agitators move the milk over the evaporator plates for cooling. The refrigerated surface area

is limited by the tank geometry and therefore, in many cases, the ability to remove heat from

the milk fast enough to meet cooling requirements with high milk loading rates is not

possible without reducing evaporator surface temperature to the point where freezing of milk

may occur. Agitating warm milk for long periods of time can also be detrimental to milk

quality. The milk cooling tank is usually not completely filled at once. A two milking tank is

designed to cool 50 % of its capacity at once, a four milking tank is designed to cool 25 % of

its capacity at once, etc. Therefore, the cooling performance depends on the number of

milking it takes to completely fill the tank, the ambient temperature and the cooling time. In

Europe, the EN standard 13732 sets different classes of cooling performance based on these

three parameters (number of milking, ambient temperatures and cooling times) as

summarized in Table. Similar classifications are given by the international standard ISO 5708

or the American standard 3A 13-10.

6

1. No. of Milking Class

2. 2-milking tank designed to cool 50% of its capacity at once

4 4- milking tank designed to cool 25% of its capacity once

6 6- milking tank designed to cool 16.7% of its capacity once

2. Ambient temperature class

Class A B C

Performance temperature 38°C 32°C 25°C

Safe Operating temperature 43°C 38°C 32°C

3.Cooling time class( maximum cooling time cool any milk (35 deg to 4 deg )

Class 0 1 2 3

Time 2 hours 2.5 hours 3 hours 3.5 hours

Table 2.1 - Performance of Bulk Milk Cooler [P2]

In 2007 F. Illan, A.Viedma analyzed milk cooling tanks in this work are assumed to be class

2 B II (milking tank designed to cool 50 % of its capacity from 35 ºC to 4 ºC in 3 hours at an

ambient temperature of 32 ºC). Three different tank capacities of 1.5, 5 and 9 m3 were

studied. Both specific heat and density of milk are influenced by its fat content and

temperature. Since the milk directly comes from the cow milking machine, it can be

considered whole milk (3.5 % fat). For a temperature range between 4 and 35ºC, the specific

heat cp of whole milk can be considered constant and equal to 3890 KJ/ kg ˚k, where its

density around 1032 considered constant 1030 kg/m3 Therefore, the cooling capacity required

to cool a n-milking tank of volume V from 35 ºC to 4 ºC in 3 hours can be obtained as:

Q = (ρm v cp ΔT)/(n Δ t) =1023 *V*3890*(35-40) /(n*3*3600) (W)

Usually milk cooling tanks had its own condensing unit, which only produces the

refrigeration effect required to cool the milk stored in one tank. The cooling capacity of any

condensing unit depends on tank volume and class and it must be at least equal to (and

normally higher than) the value obtained applying equation. In this work it had been assumed

that this cooling capacity is strictly equal to the minimum. Summarizes the main

characteristics of the cooling tanks (condensing units included) analyzed in this work.

Model Volume Class Cooling Refrigerant Energy 7

capacity charges consume

1500L 1.5m^3 2B2 8.64 8.16kg 4.39kw

5000L 5m^3 2B2 28.79 19.94kg 14.64kw

9000L 9m^3 2B2 51.82 29.91kg 26.35kw

Table 2.2 - Characteristic of Cooling Tank [P2]

In 2009 hazard chilling centre Bhopal installed 5000 L bulk milk cooler It is bulk milk cooler

with direct expansion cooling system. The cooling unit of bulk cooler adequate design to cool

milk from 35˚ to 4˚ according ISO 5708 norms. The compact condensing unit is simple easy

to install comprise reliable hermetic compressor operating 0˚c evaporator and 50˚condensing

temperature (Alfa level) and charged with 14 kg of Freon 22 which is injected by the

expansion valve in evaporator. For this calculation bulk milk cooler isentropic efficiency

0.80. Compressor and motor efficiency 1.00 and cooling capacity28.64kw this value taken

from Alfa level limited (Replacing harmful refrigerant R22 in bulk milk cooler volume 2

Indian journals of science and technology).

Refrigerant M(kg/sec) P(kW) Qk (kW) R.E (kJ/kg) COP

R22 .207 10.62 39.25 138.41 2.87

R134a .232 10.77 39.40 123.60 2.66

R152a .135 10.08 38.71 212.24 2.84

R717 .028 9.99 38.52 1009.36 2.87

R143a .288 12.83 41.46 99.43 2.23

R32 135 11.41 40.04 212.08 2.51

R290 .125 11.10 39.76 236.60 2.57

Table 2.3 - Comparison of Various Refrigerants used in 5oooL Bulk Milk Cooler [P1]

2.3 TEST SETUP REQUIRED FOR BULK MILK COOLER AS PER ISO

5708:1983 [B5]:8

The test room is suitable for testing the Bulk Milk Coolers up to the maximum capacity of

5000 LPD under 2AII conditions as specified in ISO 5708: 1983, as far as the Cooling Tests

are concerned.

The room temperature can be set within the range of 15ºC to 50ºC with the stability of

±0.2ºC.

2.3.1 The Setup for Bulk Milk Cooler Consists of:

1. An Insulated Room made from Sandwich Panels measuring 4.5 M X 4.5 M X 4 M

Height.

2. A Semi-hermetic Water Chiller of nominal 35HP rating (with water cooled

condenser) or of nominal 40HP rating (if the air cooled condenser is used). The

refrigerant used is R22.

3. Hot & Cold Tank Arrangement for the chiller so that the room temperature is

maintained within ±0.2ºC and the temperature gradient around the test piece is within the

limits of ISO 5708: 1983 section 15.1.

4. A Vertical Inline Pump of Grundfos make, for circulating the water from the cold

tank to the Refrigerant to Water PHE and back.

5. A Vertical Inline Pump of Grundfos make, for circulating the conditioned water from

the hot tank to the water cooling coil located inside the air handling unit and back to the

hot tank.

6. An Air Handling Unit Assembly located at the roof of the room consisting of a blower

of adequate capacity and a water cooling coil and the heaters. The air is delivered thru

the perforated wall and is sucked from the opposite wall. This ensures uniform air

velocity and air temperature across the length, breadth and the height of the room. The

arrangement easily satisfies the temperature uniformity and maximum air velocity

requirements of ISO 5708: 1983 section 15.1.

7. PID Control System for the control of the room temperature consisting of Siemens

make Three Ways Flow Control Valve, Thyrister for modulating the room air heaters,

and a PID controller. The Heat-Cool Control is used so as to keep the running cost to the

minimum.

8. Yokogawa make Data Acquisition System and the sensors like RTD PT100 for

mapping of the air temperature around the tank under test and the condensing unit as per

9

ISO 5708: 1993 section 15.1.2 and 15.1.3, pressure and temperature sensor for the

measurement of the parameters at the evaporator inlet (ISO 5708:1983 section 19.2).

9. Sensors (Transducers) for the measurement of the electrical parameters such as the

voltage, frequency, power consumption and the integrated power for calculating the

power consumption of the bulk milk cooler on per liter basis as per ISO 5708: 1983

section 21.1.1.9. The transducers are connected to Data Acquisition System as

explained in ‘h’ above. Specified starting point such as 35 ºC or 19 ºC, consisting of the

heaters, pump and a PID Controller.

10. A Computer consol and the Data Acquisition software based on National

Instruments, USA LAB View®.

11. The setup is designed to work 24 hours a day and 7 days a week.

12. The setup is user friendly and has the provision to make all the operations from the

computer terminal.

13. A Milk (Water) Heating System, to raise the temperature of the water to the tripping

signals is indicated on the computer monitor whenever a safety device trips or a

parameter exceeds the preset limit. ISO 5708: 1983 requirements such as filling the tank

under test with the correct milk/water quantity within the prescribed time period, etc. are

out of the scope of our supply

2.3.2 Specification of Pre-Fabricated Wall:

The test room is of prefabricated type with tongue and groove joints and silicone sealant at

the joints. Given below are the specifications.

Size of the room : Length 4.5M X Breadth 4.5M X Height 4M

Insulation thickness : 80MM PUF all over, 40 ±2 kg/m3 Density.

Cladding, Inside : Galvanized & pre-coated Steel Sheets, 0.6MM thick

Cladding, Outside : Steel Sheets, 0.6MM thick, percolated galvanized

Flooring : 0.6MM thick pre-coated sheets outside, PUF insulation &

12MM Marine plywood with FRP coating. 1.5MM Stainless

Steel Sheet above.

Door : User to specify the size. Has glass viewing window, one each

for indoor and outdoor rooms. Heavy duty hinges, latches and

gaskets are provided for proper sealing.

Conditioned Air Delivery: From perforated wall.

10

Air Suction : From the opposite wall.

Illumination : 40W X 4 tubes with decorative fittings.

Floor of the room : made from heavy gage SS sheets and can withstand the loading

of 800 kg/m3.

Roof of the room ; The conditioning equipment (AHU) is strategically located

2.4 HEAT LOAD DESIGN [P2, P6, B3]:

According to carrier air conditioning company primary function of air conditioning is to

maintain human comfort or require by product or process within a space. To perform this

function equipment must be installed proper capacity. The purpose of calculating heat load is

important choosing system component such as chiller, pump, air handling unit carrier (1987)

, Aybers (1992) stated that choice of ideal cooling system requires good calculation heat load

and all source of heat must be take into consideration. According to Erol (1993) determines

all inputs of heat load would not be possible for this reason, there may be some deviation in

the heat load and focus point must be minimizing deviation. The capacity of compressor must

be enough to suck and pump cooling gas to compressor ( sava 1987). For calculating heat

load of the environment detailed construction design information used as a testing room.

Anonymous (1998).

2.5 VARIABLE FLOW CHILLER WATER PUMPING [P5, P7]:

The principal objectives of chilled water pumping system selection and design are to provide

the required cooling capacity to each load, to promote the efficient use of refrigeration

capacity in the plant, and to minimize pump energy consumption subject to whatever

budgetary constraints may apply. In the typical design process, such decisions are made on

the basis of economic calculations. Accurate energy use prediction is an essential step in the

development of the operating cost component of such analyses. Typically, flow is at a

constant flow rate or in increments such that flow through active evaporators of chillers is

constant while flows vary in proportion to the cooling load to reduce the part load energy

consumption of pumps. Primary/secondary systems with constant flow have been converted

into variable flow systems by introducing a valve into the bypass line to permit flow only

from supply to return (Avery 1998), a practice that have received universal approval from the

design community (Rishel 1998). Multiple chillers are generally connected in parallel,

although some plants employ series arrangements.

11

2.6 PIPING DESIGN: ASHARE STANDARD 90.1(2001) STATES [B1, B2]:

6.3.2.2.2: two pipe changes over system that use a common distribution system to supply

both heated and chilled water is acceptable provide all the following met system is built.

Many designers consider humidity control through reheat In October of 2000 the Trane

company is said modern two pipe arrangement is arranged for ease of balancing in almost all

area . Modern two pipe system does not vary much changes in load show up as variation in

the system delta T . In this two pipe chiller water system divide the flow of two chillers same

way two condensing unit required for particular one unit chiller and return from air handling

unit suck two unit of chiller, water is recalculated in the system

Figure 2.1 - Two Piping Systems in Chiller Arrangement [B2]

Piping materials and design have a large influence on the system pressure drop, which in turn

affects the pump work. Many of the decisions made in the piping system design will affect

the operating cost of the chiller plant every hour the plant operates for the life of the building.

When viewed from this life cycle point of view, any improvements that can lower the

operating pressure drop should be considered. Some areas to consider are pipe size, pipe

material, valve, direct return vs reverse return. Three pipe systems with a common return for

heating and cooling are not allowed. (6.3.2.2.1)

Pipe joint: According to division 15, 15060 HVAC pipe

1. Threaded joint:

12

a. Thread pipe with tapered pipe threads in accordance with ANSI B2.1. Ream threaded

ends to remove burrs. Apply pipe joint sealant (Rector Seal No. 5) or Teflon tape

suitable for the service for which the pipe is intended on the male threads at each joint.

Teflon tape shall not be used for oil services.

2. Welded Joints

a. Weld pipe joints in accordance with ASME Code for “Power Piping,” B31.1.

b. Whenever welded piping connects to equipment valves or other units needing

maintenance, servicing, or possible removal, flange the connecting joints. Match the

pressure rating of the pipe flanges with the pressure rating of the flanges on the

equipment to which the piping connects. Provide flanged pipe sections to permit removal

of equipment components.

c. Welding Process: Sizes 4 inch and smaller, use either gas welding (oxyacetylene

process) or metallic arc process; sizes above 4 inches, use metallic arc process.

d. Beveling and Welding: All pipe 2½ inches and larger may be purchased mill beveled or

shall be machine beveled on both ends before welding. On odd lengths of pipe, beveling

may be accomplished by means of the oxyacetylene cutting torch provided all paint, rust,

scale and oxide are carefully removed with hammer, chisel or file and bevel left smooth

and clean. Joints shall be prepared and welded to assure thorough fusion of alignment

and the production of a joint that shall develop the full strength of the pipe and that shall

be leak proof in service.

e. Welding Rods: The welding rod used for welding steel and wrought iron shall be

approved welding rod in accordance with ASTM Spec. A233. Electrodes of

Classifications E6012, E6013, E7014 and E7024 shall not be used.

f. Repair of Welds and Weld Defects

1) A weld is considered defective and shall be repaired if it does not meet the acceptance

standard of each applicable non-destructive examination as defined ASME/ANSI

B31.9.

2) Repairs shall be made in accordance with ASME/ANSI B31.9.

3) Brazed Joints: For copper tube and fitting joints, braze joints in accordance with the

AWS “Soldering Manual”, the Contractor’s tested Procedure Qualification Record,

ANSI B31.1 – Standard Code for Pressure Piping, “Power Piping”, and ANSI B9.1 –

Standard Safety Code for Mechanical Refrigeration.

13

4) Soldered Joints: For copper tube and fitting joints, solder joints in accordance with the

AWS “Soldering Manual” and “The Copper Handbook.” Thoroughly clean tube

surface and inside surface of the cup of the fittings, using very fine emery cloth, and

prior to making soldered joints. Wipe tube and fittings clean and apply flux. Flux shall

not be used as the sole means for cleaning tube and fitting surfaces.

2.7 HVAC CONTROL [B9]:

It was only natural that the first HVAC controllers would be pneumatic, as the engineers

probably understood fluid control. Thus mechanical engineer could use their experience with

the properties of steam and air to control the flow of heated or cooled air. There are still

pneumatic HVAC systems in operation in some buildings, such as schools and offices, which

can be a century old.

After the control of air flow and temperature was standardized, the use of electromechanical

relays in ladder logic to switch dampers became standardized. Eventually, the relays became

electronic switches, as transistors eventually could handle greater current loads. By 1985,

pneumatic control could no longer compete with this new technology.

By the year 2000, computerized controllers were common. Today, some of these controllers

can even be accessed by web browsers, which need no longer be in the same building as the

HVAC equipment. This allows some economies of scale as single operations center can

easily monitor thousands of buildings.

14

CHAPTER 3: AIR CONDITIONING SYSTEM

3.1 WHAT IS AIR CONDITIONING?

Heating ventilating and air-conditioning HVAC is one of the building mechanical services

that include plumbing, fire protection, and escalators. Air-conditioning refers to any form of

cooling, heating, ventilation or disinfection that modifies condition of air. the goal of an

HVAC system is to provide an energy efficient, cost effective, healthy and comfortable

indoor environment with acceptable indoor air quality.

3.2 AIR CONDITIONING SYSTEMS CLASSIFICATION:

Corresponding to their related equipment Air conditioning systems may be classified as:

1. Central systems.

2. Decentralized systems;

According to the method by which the final within the space cooling and heating are

attained, air conditioning systems are generally divided into four basic types:

1. All-air system when energy is transferred only by means of heated or cooled air.

2. All-water system when energy is transferred only by means of hot or chilled water.

3. Air-water system when energy is transferred by a combination of heated/cooled air and

hot/chilled water

4. Unitary refrigerant based system when energy is transferred by a refrigerant

3.3 CENTRAL AIR CONDITIONING SYSTEMS:

A central HVAC system serves one or more thermal zones and has its major components

located outside the zone or zones being served in some convenient central location in the

building or near it. District systems serving more than one building revert to central systems

at the single building level.

3.3.1 Central Air Conditioning Systems Components:

Central air conditioning systems basically consist of three major parts:

1. An air system or air handling unit (AHU), air distribution system (air ducts) and

terminals.

2. Water system – chilled water system, hot water system, condenser water system

15

3. Central plant – refrigeration (chiller) plant, boiler plant

3.3.2 Advantages of Central Air Conditioning Systems:

• Allow major equipment components to be isolated in a mechanical room (i.e. Allows

maintenance to occur with limited disruption to building functions, reduce noise and

aesthetic impacts on building occupants).

• Offer opportunities for economies of scale.

• Larger capacity refrigeration equipment is usually more efficient than smaller capacity

equipment; larger systems can utilize cooling towers that improve system efficiencies in

many climates.

• Central systems may permit building-wide load sharing resulting in reduced equipment

sizes, costs, and the ability to shift conditioning energy from one part of a building to

another.

• Central systems are amenable to centralized energy management control schemes; i.e.

reduced building energy consumption.

• A central system may be appropriate for other than climate control perspective; active

smoke control is best accomplished by a central all-air HVAC system.

3.3.3 Disadvantages of Central Air Conditioning Systems:

• As a non-distributed system, failure of any key equipment component mayaffect the

entire building.

• As system size and sophistication increase, maintenance may become more difficult and

may be available from fewer providers if specialists are needed.

• Large centralized systems tend to be less intuitive making systems analysis and

understanding more difficult

3.4 DECENTRALIZED SYSTEMS:

Decentralized systems may be divided into:

1. Individual Systems using self-contained, factory-made air conditioner to serve one or

two rooms.

2. Unitary Systems, which are similar in nature to individual systems but serve more

rooms or even more than one floor, have an air system consisting of fans, coils, filters,

ductwork and outlets (e.g. In small restaurants, small shops and small cold storage

16

rooms). The term packaged air-conditioner is sometimes used interchangeably with the

unitary air-conditioner. The air-conditioning and refrigeration institute ARI defines

unitary air-conditioners one or more factory-made assemblies that normally include an

evaporator/cooling coil and a compressor and condenser combination.

3.4.1 Advantages of Decentralized Air Conditioning Systems:

1. Serving only a single zone, decentralized HVAC systems will have only one point of

control typically a thermostat for active systems.

2. Each decentralized system generally does its own thing, without regard to the

performance or operation of other decentralized systems.

3. Decentralized systems tend to be distributed systems providing greater collective

reliability than do centralized systems

3.4.2 Disadvantages of Decentralized Air Conditioning Systems:

1. Decentralized system units cannot be easily connected together to permit centralized

energy management operations.

2. Decentralized systems can usually be centrally controlled with respect to on-off

functions through electric circuit control, but more sophisticated central control (such as

night-setback or economizer operation) is not possible.

3.5 APPLIED PSYCHOMETRICS:

The practical data to properly evaluated the heating and cooling loads They also recommend

outdoor air quantities for ventilation purpose in area where state city, or local code does not

exist

Description of various terms, process and factor –as encounter in normal air conditioning

application

Dry bulb temperature – The temperature of air is as register by an ordinary thermometer

Wet bulb Temperature – The temperature register by thermometer whose bulb is covered by

wetted wick and exposed to a current of rapidly moving air

Dew point temperature – The temperature at which condensation of moisture begins when

air is cooled

Relative humidity - Ratio of actual water vapor pressure of air to the saturate water vapor

pressure at same temperature

17

Specific humidity or moisture content – The weight of water vapor in grains or pound of

moisture per pound of dry air

Enthalpy –a thermal property indicating quantity of heat in the air above arbitrary datum in

Btu per pound of dry air. The datum for dry air is 0°F and for moisture content, 32°F water

Enthalpy deviation – Enthalpy indication above for any given condition is enthalpy of

saturation, it should be corrected by enthalpy deviation due to air not being saturated state.

Enthalpy in Btu per pound of dry air, Enthalpy deviation applied where extreme accuracy is

required on normal air conditioning system they omitted.

Specific volume – The cubic feet of the mixture per pound of dry air

Sensible heat factor – The ratio of sensible heat to total heat

Alignment circle – Locate 80F dry bulb temperature and 50% relative humidity and used in

conjunction with the sensible heat factor to plot various air condition process line

Pound of dry air – The basic for all psychometrics calculations remains constant during all

psychometrics process The dry bulb, wet bulb, dew point temperature and the relative

humidity are so related that if two properties are known, all other properties shown may then

determined. When the air is saturated dry bulb, wet bulb, and dew point temperature are all

equal.

3.6 DESCRIPTION OF TERMS, PROCESS AND FACTORS:

3.6.1 Sensible Heat Factor:

The thermal properties of air separated from latent heat & sensible heat .the term sensible

heat factor is the ratio of sensible heat to total heat, where total heat is sum of sensible heat

load and latent heat load. This ratio mat be expressed as

SHF = SH/ (SH+LH) =SH/TH

Where SHF = sensible heat factor

SH = sensible heat

LH = latent heat

TH = total heat

3.6.2 Room Sensible Heat Factor:

The room sensible heat factor is the ratio of room sensible heat the summation of room

sensible heat and room latent heat. The ratio is expressed following formula

RSHF = RSH/ (RSH+RLH) =RSH/RTH

18

The supply air to a conditioned space must have the capacity to offset simultaneously both

room sensible heat and room latent heat .The room and supply air condition to the space

may be plotted on the standard psychometrics chart and these point connect straight line ( o-

c) shown in figure 3.1 . The line represents the psychometrics process of the supply air within

condition space and is called sensible heat factor line. The slope of RSHF line illustrates the

ratio of sensible to latent load within the space and is illustrating in fig ∆hs (sensible heat)

and ∆hl (latent heat)

Figure 3.1: Sensible Heat Factor Lines [B3]

3.6.3 Effective Sensible Heat Factor (ESHF);

To relate bypass factor and apparatus dew point to the load calculation, the sensible heat

factor term developed. ESHF is interwoven with BF and ADP and thus greatly simplified the

calculation of air quantities and apparatus selection. The effective sensible heat factor is the

ratio of effective room sensible heat to effective room sensible and latent heats. Effective

room sensible heat is composed of room sensible heat plus the portion of outside air sensible

load which is considered as being bypassed unaltered through condition space. The effective

room latent heat is composed of room latent heat plus the portion of outside air latent heat

load which is considered as being bypassed unaltered through conditioned space. The ratio is

expressed in the following formula

ESHF = ERSH / (ERSH+ERLH) = ERSH/ERTH

3.6.4 Air Quantities using ESHF, ADP, and BF:

19

A simplified approach for determining the required air quantity is to use psychometrics

correlation of effective sensible heat factor apparatus dew point and bypass factor .ERSH, BF

and ADP with GDHF and RSHF, These two factor need not be calculated to determine the

required air quantities, since the use of ESHF, BF and ADP (supply temperature) result in

same air quantities. The formula for calculating air quantities’ using BF and supply

temperature

CFM = ERSH / 1.08(Trm – Tadp) (1-BF)

The air quantities simultaneously offset the room sensible and room latent loads and also

handles the total sensible and latent loads for which the conditioning apparatus is designed

including outdoor air load and supplementary loads

20

CHAPTER 4: HEAT LOAD CALCULATION

The primary function of air condition is to maintain condition that are (1) conductive to

human comfort (2) require by product or process within a space. To perform this function,

equipment of the proper capacity must be installed and control through the year. The

equipment capacity is determined by actual instantaneous peak load requirement; type of

control is determined by the conditions to be maintained during peak and partial load. An

accurate survey of load components of the space to be air conditioned is a basic requirement

for realistic estimate of heating loads. The completeness and accuracy of this survey is the

very foundation of the estimate.

21

Figure 4.1: Top View of Test Room

22

4.1 SUMMER SEASON:

4.1.1 Inside Design Condition:

For this application we have to design heat load as per inside design temperature, humidity

and equipment load for different type of bulk milk cooler.

10˚c DBT 55% RH

Equipment load 21TR Maxi 10, 000 L BMC

4TR Mini 500L BMC

Plant Size 32.31ft (9.85 m)*14.43 ft (4.40 m)*10.48 ft (3.19 m)

4.1.2 Outside Design Condition:

Maximum summer design condition are recommended for laboratories and industrial

applications where exceeding the room design conditions for even short period of time can be

determinate to a product or process. The maximum design dry bulb and wet bulb temperature

is simultaneous peak. E ach of this condition can be expected to be exceeded no more than 3

hours in a normal summer. Data for Anand at 20˚ Latitude.

SUMMER(May) WINTER(January)

DB WB RH% DB WB RH%

˚C 44 25.6 24 15.6 6.1 58

˚F 111.2 78 24 60.08 43 58

Table 4.1 - Outside Design Temperature [B6]

4.2 SENSIBLE HEAT:

4.2.1 Solar Heat Gain through Glass:

For a given application there is a no glass in the system, that area of glass is zero so give no

overall heat transfer through glass.

4.2.2 Heat Gain through Building Structure:

23

Heat gain through the exterior construction (walls and roof) is normally calculated at greatest

heat flow. It is caused by solar heat being absorbed at exterior surface and by temperature

difference between outdoor and indoor air. Both heat source are highly variable thought any

one day and therefore, result in unsteady state heat flow through the exterior construction.

This unsteady state flow is difficult to evaluate for each individual situation; however, it can

be handle heat by means of an equivalent temperature across the structure. The heat flow

through the structure may then be calculated, using the steady state heat flow equation with

equivalent temperature difference.

Q= heat flow, Btu/hr, Watt

U =transmission coefficient Btu/hr (ft^2) (˚F), Watt/m^2˚k

A = area of surface, ft^2, m^2

ΔT= equivalent temperature difference, ˚F, ˚C

Facing Area

ft2 (m2)

U

Btu/hrsqft˚F

(Watt/m^2˚K)

Temp diff

˚F(˚C)

Load

Btu/hr (Watt)

North

151.23

(14.05)

0 .4(2.27)

65(36.09) 3931.98

(1151.33)

East 0.0

South 0.0

West 0.0

North East 0.0

South East 0.0

South West 0.0

North West 0.0

Roof Sun

1. Wall

U = 0.4 Btu/hr ft2 ˚F for 9" brick =2.27 Watt/m^2˚K

= 0.2 Btu/hr ft2 ˚F for building with rigid board insulation

Total Q=3931.98 Btu/hr = 1151.33 Watt

24

4.2.3 Transmission Heat Gain except Walls:

Heat flow through the interior construction (floor, ceiling and partitions) is caused by

difference in temperature of the air on both side of structure. This temperature difference is

essentially constant thought the day and therefore, the heat flow can be determined from

steady state heat flow equation, using the actual temperature on either side.

1. Partition

For partition for 9” brick U= 1.7W/m^2k = 0.29Btu/hrft^2F

For partition for 4” brick U= 2.56 W/m^2 k = 0.45Btu/hrft^2F

For partition for masonry U= 3.97 W/m^2 k =0.69Btu/hrft^2F

2. Floor

For floor without ceiling U=3.41W/m^2 k=0.6Btu/hrft^2F

For floor with ceiling U= 2.27 W/m^2 k=0.4Btu/hrft^2F

For floor on ground U=0

A. Ceiling

B. Partition

ΔT = Outside design-inside design-5

C. Floor

Total Q=14552.17Btu/hr=4261.03 Watt

4.2.4 Infiltration and Ventilation Heat:

25

Infiltration of air and particular moisture into conditioned space is frequently a source of

sizable heat gain or loss. The quantity of infiltration air varies according to tightness of door

and window , building, velocity of air .and no of people, duration of occupancy, nature of

activity , any special concentration ,.At times, it is required to estimate the number of people

on the basis of square feet per person ,or on average traffic given by following equation.

1. Outside air:

We have to consider 1 air charges per hour infiltration in the system.

2. Ventilation standard:

Application SmokingCFM(CMH) per person CFM per sq

ft of floorRecommended Minimum

Hospital none 30(50.97) 25(42.48) .33

Office some 15(25.49) 10(16.99) -

Restaurant considerable 12(20.39) 10(16.99) -

Laboratories some 20(33.98) 15(25.49) -

Kitchen - - - 4.0

Table 4.2 - Ventilation Standard [B3]

Total Q=1007.30Btu/hr =294.95 Watt

26

4.2.5 Internal Heats:

Internal heat gain is the sensible and latent heat released within the air condition by the

occupants, light, appliance and pipe

1. People:

Heat is generated within human body by oxidation called metabolism rate. Metabolism rate

vary with person and his activity level

Q= no of people *heat rate (Btu/hr)

ActivitySensible heat

(Btu/hr)(Watt)

Latent heat

(Btu/hr)(Watt)

Total heat

(Btu/hr)(Watt)

Office work 245(71.74) 205(60.03) 450(131.77)

Standing , light work 255(74.67) 187(54.76) 442(129.43)

Heavy work 580(169.83) 870(254.75) 1450((424.58)

Athletics 716(209.65) 1075(314.77) 1791(524.42)

Table 4.3 - Internal Heat from Person for Various Activities [B3]

We have to take office work condition and there are three people work in the test facility.

2. Light: light conversion of sensible heat by conversion of electric power into light and heat

.The heat is dissipated by radiation surrounding surface by conduction and convection to

surround air

Types Heat Gain Btu/hr

Florescent Total light watt *1.25*3.4

Incandescent Total light watt*3.4

Here this which light is taken in testing room so assume 1 W/ft^2

27

3. Equipment: In the testing room equipment is bulk milk cooler , total heat released from

10kl bulk milk cooler is 21 TR heat from standard table .

4. Appliance: there is no appliance in the system

Total Q=254320.182 Btu/hr =74467.61 Watt

Room subtotal heat Q=273811.64 Btu/hr =80174.92 Watt

10% Safety Q= 27381.16 Btu/hr =8017.49 Watt

Effective room sensible heat Q= 301192.80 Btu/hr= 88192.41 Watt

4.3 LATENT HEAT

4.3.1 People:

Heat is generated within human body by oxidation called metabolism rate. Metabolism rate

vary with person and his activity level.

4.3.2 Outside Air:

Outside heat that bypasses the cooling coil contain moisture give latent heat and this outside

air is calculated from infiltration and ventilation.

Total Q=1296.89Btu/hr =379.74 Watt

5%Safety Q=64.85 Btu/hr =18.99 Watt

Effective room latent heat Q=1361.73Btu/hr=398.73 Watt

4.4 OUTSIDE AIR HEAT:

28

Outside heat is total of outside sensible heat and outside latent heat can be determined by

GRAND TOTAL HEAT= SENSIBLE HEAT+ LATENT HEAT+ OASH+ OALH

GTH Q =314942.005 Btu/hr

=26.24TR

=92.22 kW

4.5 APPRATUS DEW POINT AND AIR QUANTITY:

4.6 PREDICTION ANALYSIS OF HEAT LOAD FOR SUMMER AND WINTER WEATHER DATA WITH

DIFFERENT CAPACITY OF BULK MILK COOLER:

Capacity of

cooler(KL)

Maximum

equipment

load (TR)

Room load (TR) Total load (TR) Chiller flow rate

required (l/s)

Summer Winter Summer Winter Summer Winter

10 21 5.25 2.7 26.25 23.7 4.96 4.48

5 11.5 5.25 2.7 16.75 14.2 3.17 2.68

3 6.5 5.25 2.7 11.75 9.2 2.22 1.74

2 4.5 5.25 2.7 9.75 7.2 1.84 1.36

Table 4.4 - Load Predictions for Summer and Winter Data

29

CHAPTER 5: CHILLER PLANT DESIGN

5.1 CHILLER BASICS:

The chiller can be water-cooled, air-cooled or evaporative cooled. The compressor types

typically are reciprocating, scroll, screw or centrifugal. The evaporator can be remote from

the condensing section on air-cooled units. This has the advantage of allowing the chilled

water loop to remain inside the building envelope when using an outdoor chiller. The chilled

water flows through the evaporator of the chiller. The evaporator is a heat exchanger where

the chilled water gives up its sensible heat (the water temperature drops) and transfers the

heat to the refrigerant as latent energy (the refrigerant evaporates or boils).

5.2 CHILLER ARRANGEMENT:

To provide some redundancy in the HVAC design, most designers will require two or more

chillers. Multiple chillers also offer the opportunity to improve on overall system part load

performance and reduce energy consumption. Parallel chiller plants are straightforward to

design and are easily modified for variable primary flow.

5.2.1 Parallel Chiller System:

Figurer shows a parallel water-cooled chiller plant. Chilled water is circulated by the chilled

water or primary pump through both chillers to the load and back to the chillers. The chilled

water loop can be either constant flow or variable flow. Variable flow systems increase the

complexity but offer significant pump work savings. They also resolve the issue about chiller

sequencing that occurs with parallel chillers, constant flow. Variable flow systems are

covered in Primary/Secondary Systems and Variable Primary Flow Design. A condenser loop

is required for water-cooled chillers. This includes a condenser pump, piping and a cooling

tower or closed circuit cooler. The condenser loop operates whenever the chillers operate.

Pumps can be constant or variable flow. The chilled water pump is sized for the design flow

rate. Figure shows one main chilled water pump providing flow to both chillers. An

alternative method is to have two smaller pumps serving dedicated chillers. Another

possibility is to lower the operating chiller’s set point to offset the mixed water temperature.

This also works but has some difficulties. Lowering the chilled water set point requires the

chiller to work harder, lowering its efficiency.

30

Figure 5.1: Parallel Flow Chillers [B3]

5.2.2 Series Chiller System:

Series chillers are another method of operating more than one chiller in a plant. This design

concept resolves the mixed flow issues found in parallel chiller designs. The chillers can be

preferentially loaded as well, allowing the designer to optimize chiller performance. Series

chiller systems are straightforward to design and operate. The flow rate through each chiller

is the entire system flow, that is, double the individual flow rate of the parallel chillers (two

chillers). This means that the chiller evaporator must accommodate the doubled water

quantity. All things being equal, this result in fewer water passes and decreased chiller

efficiency. However, this efficiency loss is more than offset by increased chiller efficiency

because the upstream chiller operates at warmer temperatures. Also, pressure losses are

additive when the chillers are piped in series. This may increase total system pressure loss

significantly. Another problem in series chiller is break down of on chiller may stop total

system operation.

31

Figure 5.2: Series Flow Chiller [B3]

5.3 PIPING BASIS:

5.3.1 Open Loop Piping System:

In open loop piping system water flow through the heat exchanger and exposed to

atmosphere such as cooling tower and air washer.

5.3.2 Closed Loop Piping System:

In closed loop piping system water flow is not exposed to atmosphere at any point but some

time contain a expansion tank that is open to the atmosphere but water area exposed is

insignificant such as chilled water system.

5.3.3 Reverse Return Vs Direct Return Piping:

Reverse return piping is designed such that the path through any load is the same length and

therefore has approximately the same fluid pressure drop. Reverse return piping is inherently

self balancing. It also requires more piping and consequently is more expensive.

32

Figure 5.3 - Reversed Return Piping [B3]

Direct return piping results in the load closest to the chiller plant having the shortest path and

therefore the lowest fluid pressure drop. Depending on the piping design, the difference in

pressure drops between a load near the chiller plant and a load at the end of the piping run

can be substantial. Balancing valves will be required. The advantage of direct return piping is

the cost savings of less piping.

Figure 5.4 - Direct Returns Piping [B3]

5.4 TYPES OF PIPING SYSTEM:

33

5.4.1 Two pipe system:

This system is composed central water cooling and heating equipment, pump, distributed

piping system and terminal control. Each terminal connected single supply and single return.

Heating and cooling required according to two pipe change over system. When designing a

system the flow and temperature for the system first calculated. The change over system

design such that high temperature water is not damage evaporator and low temperature

chilled water not damage boiler.

5.4.2 Three Pipe System:

In three pipes system there is two supplies separate for hot and cold arrangement and

common return system. Three way valves are for control supply temperature as per

application required and modulating flow. Three pipe systems many were proved there is

common return hot and cold arrangement will excessive waste energy.

5.4.3 Four Pipe System:

In the four-pipe common load system, load devices are used for both heating and cooling as

in the two-pipe system. The four-pipe common load system differs from the two-pipe system

in that both heating and cooling are available to each load device, and the changeover from

one mode to the other takes place at each individual load device, or grouping of load devices,

rather than at the source. Thus, some of the load systems can be in the cooling mode while

others are in the heating mode. There is a two different pumping system is required for two

different two pipe system. Although many of these systems have been installed, many have

not performed successfully due to problems in implementing the design concepts and high

costly for given system. Another disadvantage of this system is that the loads have no

individual capacity control as far as the water system is concerned. That is, each valve must

be positioned to either full heating or full cooling with no control in between.

5.5 FLOW CALCULATION:

34

For water chilling system flow required to cool sensible heat and latent heat of load (total

load in the system) is calculated by following equation

W = 88.23 GPM=5.56l/s

Select the flow required in the system is 90 GPM =5.67 l/s

For a system we use two pipe arrangement systems so that flow is divided in equal part into

two different chiller that required 45 GPM (2.83 l/s)/45 GPM (2.83 l/s) in two pipe

changeover system.

Recommended pipe size according to calculated flow required in the system

Design water quantity

GPM (l/s)

Required pipe

nominal size (in)

240(15.12) 4

227(14.30) 4

214(13.48) 4

160(10.08) 3

142(08.95) 3

060(03.78) 2

040(02.52) 2

Table 5.1 - Pipe Size for Required Flow Rate [B3]

Form chart calculate friction loss feet /100 feet using 40 schedule steel pipe 2 in and 45 GPM

water flow 3.6 feet /100 feet of water as limit of ASHARE recommended friction loss rate 1

to 4 feet/100 feet chilled water system. Most of system is design 2.5 feet/100feet friction loss

wand velocity from graph 5.2ft/s. this is within the limit of so system selected pipe size is ok.

35

Figure 5.5: Friction Loss Chart for 40 Schedule Steel Pipe [B3]

36

For a Standard Data for Steel Pipe

U.S

Nominal

size (in)

Nominal

size in

mm

Schedule Wall

thickness

t, mm

Inside

diameter

d, mm

Surface

area

m2/m

Working

pressure kPa

(gauge)

1/4 8 40ST 2.24 9.25 0.029 1296

80XS 3.20 7.67 0.024 6006

3/8 10 40ST 2.31 12.52 0.054 1400

80XS 3.20 10.74 0.054 5654

1/2 15 40ST 2.77 15.80 0.050 1476

80XS 3.73 13.87 0.044 5192

1 25 40ST 3.38 26.64 0.084 1558

80XS 4.55 24.31 0.076 4427

2 50 40ST 3.91 52.50 0.165 1586

80XS 5.54 49.25 0.155 3799

Table 5.2 - Standard Steel Pipe Data [B2]

Pressure Calculation:

For a centrifugal pump 25 mwc pressure required in the system is given by following

equation

Head (ft) = Pressure (psi)*2.31/specific gravity

Newtonian liquids have specific gravities typically ranging from 0.5 (light, like light

hydrocarbons) to 1.8 (heavy, like concentrated sulfuric acid). Water is a benchmark, having a

specific gravity of 1.0.

Head (ft) = Pressure (psi)*2.31/specific gravity

82 =P*2.31/1.0

P=2.45 bar

5.6 TYPE OF HEAT EXCHANGERS:

37

Most heat exchangers for HVAC&R applications are counter flow shell-and-tube or plate

units. While both types physically separate the fluids transferring heat, their construction is

very different, and each has unique application and performance qualities.

5.6.1 Shell and Tube Heat Exchanger:

Figure 5.6 shows the counter flow path of a shell-and-tube heat exchanger. The fluid at

temperature T1 enters one end of the shell, flows outside the tubes and inside the shell, and

exits at the other end at temperature T2. The other fluid flows inside the tubes, entering one

end at temperature t1 and exiting at the opposite end at temperature t2. In a shell-and-tube

heat exchanger, a tube bundle assembly is welded or bolted inside a tubular shell. The bundle

is constructed of metal tubes mechanically rolled or welded at one (U-tube) or both ends

(straight-tube) into tube sheet(s) that function as headers. The shell is usually a length of pipe

that has inlet and outlet connections located along one or more of its longitudinal centerlines.

The shell is flanged at one or both open ends to accommodate a head assembly. The tube

bundle is positioned between the shell and head assemblies such that the tube wall of the

bundle mechanically separates the two flow paths. The tube bundle is assembled with tube

supports, which are held together with tie rods and spacers. Units with liquid on the shell side

have baffles for tube supports that direct the flow. Condensers must have baffles that have

been notched on the bottom to allow the liquid condensate to flow freely to the exit nozzle.

The head assembly directs the other fluid across the tube sheet(s) into and out of the tube

bundle. Head assemblies are designed with pass partitions to isolate sections of the tube

bundle such that the fluid must traverse the length of the unit one, two, four or more times

before exiting. One of two types of head assemblies is mechanically attached to the shell.

Units with multiple tube-side pass construction have a head with both an inlet and outlet

connection bolted at one end with a welded cap (U-tube) or bolted reversing head (straight-

tube) at the opposite shell end. Single-pass units have an inlet head attached atone shell end

and an outlet head attached at the other end. Many variations of the shell-and-tube design are

available, some of which are described in the following paragraphs. U- Tube. Figure 5.7

shows a U-tube removable-bundle shell and-tube heat exchanger. These units are commonly

called converters. Illustrate modifications of the U-tube design. Tank heaters are U-tube heat

exchangers with the shell replaced by a mounting collar, which is welded to a tank. A hot

fluid or steam flows inside the tubes heating the fluid in the tank by natural convection. The

tank heater manufacturer should be consulted about optimizing the bundle length. While it is

38

desirable for the bundle to significantly extend into the tank the designer must consider the

need for additional bundle support. Tank suction heaters differ from tank heaters because

they have an additional opening that permits the fluid being heated to be pumped across the

outside tube wall resulting in improved thermal performance. Figure 5.10 shows two

common designs of straight-tube, shell-and-tube exchangers, one with a fixed and the other

with a removable tube bundle assembly .Some straight-tube, shell-and-tube heat exchangers

have a floating head bolted with a gasket to a floating tube sheet or a shell-side expansion

joint. This configuration is expensive and is rarely specified in HVAC applications. The tubes

in this heat exchanger are coiled in a helical configuration around a small core. A spacer is

placed between the tube layers. In some designs the tubes have an oval cross section. These

heat exchangers are very compact and have a relatively large surface area for their size.

Figure 5.6: Counter Path in Shell and Tube Heat Exchanger [B2]

39

Figure 5.7: U- Tube Shell and Tube Heat Exchanger with Removable Bundle Assembly

and Cast “K” Pattern Flanged Head [B2]

Figure 5.8: U-Tube Tank Heater with Removable Bundle Assembly and Cast Bonn

Head [B2]

Figure 5.9: U-Tube Tank Suction Heater with Removable Bundle Assembly and Cast

Flanged Head [B2]

Figure 5.10: Straight-Tube Floating Tube sheet Shell-and-Tube Heat Exchanger with

Removable Bundle Assembly and Fabricated Channel Heads [B2]

5.6.2 Plate Type Heat Exchanger:

Plate heat exchangers consist of metal plate pairs arranged to provide separate flow paths

(channels) for two fluids. Heat transfer occurs across the plate walls. The exchangers have

40

multiple channels in series that are mounted on a frame and clamped together. The

rectangular plates have an opening or port at each corner. When assembled the plates are

sealed such that the ports provide manifolds to distribute fluids through the separate flow

paths. Illustrates the flow paths the multiple plates, called a plate pack, are supported by a

carrying bar and contained by pressure plates at each end. The design of the carrying bars and

pressure plate permit the units to be opened for maintenance or the addition or removal of

plate pairs. The adjoining plates are gasket, welded, or brazed together.

Gasket plate heat exchangers are typically limited to design pressures of 2 MPa. The type of

gasket material used limits the operating temperature. Brazed plate units are designed for

pressures up to 3 MPa and temperatures up to 260°C.

The most common plate heat exchanger is the gasket plate unit. Typically, nitride butyl

rubber (NBR) gaskets are used in applications up to 110°C. Ethylene-propylene terpolymer

(EPDM) gaskets are available for temperatures up to 160°C. The gaskets are glued or clipped

onto the plates. The gasket pattern on each plate creates the counter flow paths illustrated in

Figure 5.11: Flow Path of Gasket Plate Heat Exchanger [B2]

5.7 SELECTION CRITERIA OF HEAT EXCHANGER:

Selection of heat exchanger depend upon list of parameter as mentioned below

41

5.7.1 Thermal Performance:

The thermal performance of a heat exchanger is a function of the size and geometry of the

heat transfer surface area. Different heat transfer surface materials also affect performance—

copper has a higher coefficient of heat transfer than stainless steel.

Flow rates (velocity), viscosity, and thermal conductivity of the fluids are significant factors

in determining the overall heat transfer coefficient U. In addition, the fluid to be heated

should be on the tube side because the overall U of a shell-and-tube unit is often reduced if

the fluid to be heated is on the shell side. Properly selected shell-and-tube heat exchangers

use tube pass options and shell-side baffle spacing to maximize velocity (turbulence) without

causing tube erosion. The ability to maximize velocity on each side of a heat exchanger is

particularly important when the flow rates of the two fluids are dissimilar. However, fluid

velocity in shell-and-tube heat exchanger is limited to avoid tube erosion. U-tube exchangers

have lower tube-side velocity limits than straight-tube units due to the thinner tube wall in the

U bends.

Plate heat exchangers typically have U-factors 3 to 5 times higher than shell-and-tube heat

exchangers. The high turbulence created by the corrugated plate design increases convection

and increases the U-factor. The plate design achieves a large temperature cross at a 1 K

approach because of the counter flow fluid path and high U-factor.

5.7.2 Pressure Drop:

Fluid velocity and normal limitations on tube length tend to result in relatively low pressure

drops in shell-and tube heat exchangers. Plate units tend to have larger pressure drops unless

the velocity is limited. Often a pressure drop limitation rather than a thermal performance

requirement determines the surface area in a plate unit.

5.7.3 Fouling:

Often excess surface area is specified to allow for scale accumulation on heat transfer

surfaces without a significant reduction of performance. This fouling factor or allowance is

applied when sizing the unit. Fouling allowance is better specified as a percentage of excess

area rather than as a resistance to heat transfer. Shell-and-tube exchangers with properly sized

tubes can handle suspended solids better than plate units with narrow flow channels. The high

fluid velocity and turbulence in plate exchangers make them less susceptible to fouling. The

42

addition of surface area (tube length) to a shell-and-tube exchanger does not affect fluid

velocity, and, therefore, has little. This characteristic makes a fouling allowance practical.

This is not the case in plate units. The number of parallel flow channels determines velocity

in a plate heat exchanger. This means that as plate pairs are added to meet a load (heat

transfer surface area) requirement, the number of channels increases and results in decreased

fluid velocity. This lower velocity reduces performance and requires additional plate pairs,

which further reduces performance.

5.7.4 Cost:

On applications with temperature crosses and close approaches, plate heat exchangers usually

have the lowest initial cost. Wide temperature approaches often favor shell-and-tube units. If

the application requires stainless steel, the plate unit may be more economical.

5.7.5 Serviceability:

Shell-and-tube heat exchangers have different degrees of serviceability. The type of header

used facilitates access to the inside of the tubes. The heads illustrated in figure 5.7, 5.9, and

5.10 can be easily removed without special pipe arrangements. The tube bundles in all of the

shell-and-tube units illustrated, except the fixed-tube sheet unit (figure 5.10), can be replaced

after the head is removed if they are piped with proper clearance. The diameter and

configuration of the tubes are significant factors in whether the inside of the tubes of straight-

tube units can be mechanically cleaned. Figure 5.11 shows a type of head that permits

cleaning or inspection of the inside of tubes after the channel cover is removed.

Plate heat exchangers can be serviced by sliding the movable pressure plate back along the

carrying bars. Individual plates can be removed for cleaning, regasketing, or replacement.

Plate pairs can be added for additional capacity. Complete replacement plate packs can be

installed.

5.7.6 Space Requirements:

Cost-effective and efficient shell-and-tube heat exchangers have small diameter, long tubes.

This configuration often challenges the designer when allocating the space required for

service and maintenance. For this reason, many shell-and-tube selections have large

diameters and short lengths. While this selection performs well, it often costs more than a

43

smaller diameter unit with equal surface area. Caution should be taken to provide adequate

maintenance clearance around heat exchangers. In the case of shell-and-tube units, space

should be left clear so the tube bundle can be removed. Plate heat exchangers tend to provide

the most compact design in terms of surface area for a given space.

5.7.7 Steam:

Most HVAC applications using steam are designed with shell and-tube units. Plate heat

exchangers are used in specialized industrial and food processes with steam.

5.8 TYPES OF CHILLER COMPRESSORS:

Most cooling systems, from residential air conditioners to large commercial and industrial

chillers, employ the refrigeration process known as the vapor compression cycle. At the heart

of the vapor compression cycle is the mechanical compressor. Its function is: 1) to pump

refrigerant through the cooling system and 2) to compress gaseous refrigerant in the system

so that it can be condensed to liquid and absorb heat from the air or water that is being cooled

or chilled.

5.8.1 Reciprocating Compressors:

Reciprocating compressors are positive displacement machines that use the reciprocating

action of a piston inside a cylinder to compress refrigerant. As the piston moves downward, a

vacuum is created inside the cylinder. Because the pressure above the intake valve is greater

than the pressure below it, the intake valve is forced open and refrigerant is sucked into the

cylinder. After the piston reaches its bottom position it begins to move upward. The intake

valve closes, trapping the refrigerant inside the cylinder. As the piston continues to move

upward it compresses the refrigerant, increasing its pressure. At a certain point the pressure

exerted by the refrigerant forces the exhaust valve to open and the compressed refrigerant

flows out of the cylinder. Once the piston reaches it top-most position, it starts moving

downward again and the cycle is repeated. These compressors are available in 3

configurations namely 1) Hermetic; 2) Semi hermetic and 3) Direct driven versions.

In a hermetic unit, the motor and compressor are enclosed in a common housing, which is

sealed. Because the components are not accessible for repair, the entire compressor unit must

be replaced if it fails. The hermetic sealed units are most common in small capacities.

44

In the semi-hermetic unit the motor is also part of the unit, however it is not sealed. Semi

Hermetic compressors have the advantage over hermetic compressors in that they can be re-

built a number of times if necessary giving a much longer service life.

In a direct drive unit the motor and compressor are separated by a flexible coupling. These

types of units utilize older technology and are not commonly used today

The main factors favoring reciprocating compressor is low cost and efficiency when applied

in low capacities. Multiple reciprocating machines can be installed for higher building loads.

Further advantages include simple controls and the ability to control the speed through the

use of belt drives. Available in both air-cooled and water cooled heat rejection

configurations, these chillers are available from 0.5 to 150 tons of refrigeration (TR).

A major drawback of reciprocating chillers is their high level of maintenance requirements in

comparison with other chiller types. Reciprocating chillers have more moving parts than

centrifugal or rotary chillers, resulting in an increased need for wear-related maintenance

activities. Reciprocating chillers also generate high levels of noise and vibration. Special

precautions must be taken to isolate the chillers from the facility to prevent transmission of

machine-generated vibrations and noise. Finally, reciprocating chillers are not well suited for

applications with cooling loads in excess of 200 tons. As the units grow in capacity, their

space requirements and first costs exceed those of other chiller types. In addition, the energy

requirements for larger units exceed that of other chillers types.

5.8.2 Screw Compressor:

Screw compressors are positive displacement machines that use helical rotors to compress the

refrigerant gas. As the rotors rotate they intermesh, alternately exposing and closing off

interlobe spaces at the ends of the rotors. When an interlobe space at the intake end opens up,

refrigerant is sucked into it. As the rotors continue to rotate the refrigerant becomes trapped

inside the interlobe space and is forced along the length of the rotors. The volume of the

interlobe space decreases and the refrigerant is compressed. The compressed refrigerant

exists when the interlobe space reaches the other end. There are two types: 1) Single and 2)

Twin screw configuration.

A single-screw compressor uses a single main screw rotor meshing with two gate rotors with

matching teeth. The main screw is driven by the prime mover, typically an electric motor.

A twin-screw compressor consists of accurately matched rotors (one male and one female)

that mesh closely when rotating within a close tolerance common housing. One rotor is

45

driven while the other turns in a counter rotating motion. The twin-screw compressor allows

better control and variations in suction pressure without much affecting the operation

efficiency. Available in air-cooled and water cooled configurations, screw chiller is available

up to 750 tons of refrigeration.

With a relatively high compression ratio and few moving parts, screw chillers are compact,

smaller and lighter than reciprocating and centrifugal chillers of the same cooling capacity.

These also offer quieter, vibration-free operation and are well known for their robustness,

simplicity, and reliability. They are designed for long periods of continuous operation,

needing very little maintenance. Screw compressors can overcome high lift when speed is

reduced, allowing energy savings without the possibility of surge as the compressor unloads.

The major drawback of screw chillers is their high first cost. For small cooling loads,

reciprocating chillers are less expensive to purchase and install; for large loads, centrifugal

chillers cost less.

5.8.3 Centrifugal Compressor:

Centrifugal compressor is a dynamic machine that uses the rotating action of an impeller

wheel to exert centrifugal force on refrigerant inside a round chamber (volute). Refrigerant is

sucked into the impeller wheel through a large circular intake and flows between the

impellers. The impellers force the refrigerant outward, exerting centrifugal force on the

refrigerant. The refrigerant is pressurized as it is forced against the sides of the volute.

Centrifugal compressors are well suited to compressing large volumes of refrigerant to

relatively low pressures. The compressive force generated by an impeller wheel is small, so

chillers that use centrifugal compressors usually employ more than one impeller wheel,

arranged in series. Centrifugal compressors are desirable for their simple design and few

moving parts.

Centrifugal chillers are categorized either as positive pressure or negative pressure machines

depending on the evaporator pressure condition and the type of refrigerant used. A chiller

using refrigerant R-22 and R-134A is a positive-pressure machine, like reciprocating chillers

centrifugal units are available in both hermetically sealed and open construction. Despite its

lower operating efficiency, the hermetically sealed unit is more widely used. Due to their

very high vapor-flow capacity characteristics, centrifugal compressors dominate the 200 ton

and larger chiller market, where they are the least costly and most efficient cooling

compressor design. Centrifugals are most commonly driven by electric motors, but can also

be driven by steam turbines and gas engines.

46

A serious drawback to centrifugal chillers has been their part load performance. When the

building load decreases, the chiller responds by partially closing its inlet vanes to restrict

refrigerant flow. While this control method is effective down to about 20 percent of the

chiller's rated output, it results in decreased operating efficiency. For example, a chiller rated

at 0.60 kW per ton at full load might require as much as 0.90 kW per ton when lightly loaded.

Since chillers typically operate at or near full load less than 10 percent of the time, part load

operating characteristics significantly impact annual energy requirements.

5.8.4 Scroll Compressor:

The scroll compressor is a positive displacement machine where refrigerant is compressed by

two offset spiral disks that are nested together. The upper disk is stationary while the lower

disk moves in orbital fashion. The orbiting action of the lower disk inside the stationary disk

creates sealed spaces of varying volume. Refrigerant is sucked in through inlet ports at the

perimeter of the scroll. A quantity of refrigerant becomes trapped in one of the sealed spaces.

As the disk orbits the enclosed space containing the refrigerant is transferred toward the

centre of the disk and its volume decreases. As the volume decreases, the refrigerant is

compressed. The compressed refrigerant is discharged through a port at the centre of the

upper disk. Scroll compressors are a relatively recent development that is rapidly overtaking

the niche of reciprocating chillers in comfort cooling. They provide small size, low noise and

vibration and good efficiency. Available in air-cooled and water cooled configurations, scroll

chiller capacity can reach approximately 30 tons or less, which makes them good candidates

for spot cooling or make-up cooling applications.

The biggest drawback is that these cannot be repaired and there have been issues of scroll

compressors losing oil at low temperatures. On relatively small sizes, these do not affect the

life cycle economics drastically

5.8.5 Recommendations:

Chillers use one of four types of compressor: reciprocating, scroll, screw, and centrifugal.

The choice leans towards reciprocating compressors for peak loads up to 80 to 100 tons.

Between 100 and 200 tons peak cooling load, two or more reciprocating compressor chillers

can be used.

47

Above 200 tons, screw compressor systems begin to become cost effective. The screw

chillers are well suited for applications demanding up to 750 TR. Above these capacities,

centrifugal chillers are generally more cost effective where water is available for heat

rejection.

Centrifugal compressors traditionally provide larger capacities typically above 750 tons. The

centrifugal machines offer highest peak load efficiency and operate reliably for applications

demanding a steady state operation. The machines are only recommended with water-cooled

condenser option.

5.9 CENTRIFUGAL PUMP:

Centrifugal type pumps are used for both condenser water and chilled water systems. They

can be either inline or base mounted. The pumps must be sized to maintain the system

dynamic head and the required flow rate. Normally, the pumps are located so they discharge

into the chiller heat exchangers.

Centrifugal pumps are non-positive displacement type so the flow rate changes with the head.

The actual operating point is where the system curve crosses the pump curve. In systems with

control valves, the system curve changes every time a valve setting changes. This is

important because the pump affinity laws cannot be used to estimate a change if the system

curve is allowed to change. Identical pumps in parallel will double the flow at the same head.

Identical pumps in series will double the head. .Basic pump curve from manufacturer decide

pump impeller size and impeller speed.

Figure 5.12: Pump Efficiency Curve [B3]

48

5.9.1 Arrangement of Pump:

In a large system, a single pump may not be able to satisfy the full design flow and yet

provide both economical operation at partial loads and a system backup. The designer may

need to consider the following alternative pumping arrangement.

1. Parallel Arrangement:

When pumps are applied in parallel, each pump operates at the same pressure and provides its

share of the system flow at that pressure. Generally, pumps of equal size are recommended,

and the parallel pump curve is established by doubling the flow of the single pump curve.

Plotting a system curve across the parallel pump curve shows the operating points for both

single and parallel pump operation single pump operation does not yield 50% flow. The

system curve crosses the single pump curve considerably to the right of its operating point

when both pumps are running.

Figure 5.13: Pump Pressure Curve for Parallel Arrangement [B3]

2. Series Pump Arrangement:

When pumps are applied in series, each pump operates at the same flow rate and provides its

share of the total pressure at that flow. A system curve plot shows the operating points for

both single and series pump operation single pump can provide up to 80% flow for standby

and at a lower power requirement.

49

Figure 5.14: Pump Pressure Curve for Series Arrangement [B3]

5.10 FLOW CONTROL SYSTEM:

Three way valves are used for regulating water liquid / water flow through heat exchanger

like cooling and heating coils, air washer etc. They have single disc on the valve stem

operating between two seats and have three ports. There are two type divesting (mixing)

valve and mixing valve. In divesting valve one connecting port is the inlet and other two are

outlet port, while in the mixing valve there two inlet ports and third one is outlet port.

5.10.1 Diverting Valve:

The diversity valve can operate as a two (open and shut) position valve and also as a

modulating valve, by changing the type of control. The bypass of the chilled water ensure

continuous water flow the chiller even if number of zone in the system do not call for cooling

and so the chilled water respective coil is stopped . A two way solenoid valve is used instead

of diversity valve, but this will be drawback of (I) when the solenoid valve goes off on room

thermostat, there is no bypass chilled water and affect the chiller and chiller will be freeze up

water. (ii) When solenoid valve goes off disturbing noise is produced as its plunger drop

down. The diverting does not produce such type of noise .so that most of system uses three

way valves instead of two way valve. If the full load valve motor move the valve to the fully

open position. As the load is come down valve motor modulate the flow. Thus chilled water

flow through cooling coil and so its capacity is modulate according to load.

50

Figure 5.16: Three Way Bypass and Mixing Valve [B2]

This valve has two inlet and one outlet port and Chilled water supply line is connected to one

inlet port and the second inlet port is connected to the return water line from cooling coil and

third port is connected to two mixing outlet . At full load there is no mixing of water and

according to load mixing process is done

In most cases, a mixing valve can perform the same function as a diverting or bypass valve if

the companion actuator has a very high spring rate. Otherwise, water hammer or noise may

occur when operating near the seat.

5.11 SELECTED EQUIPMENT:

According to design we required 30 TR chiller, Apparatus temperature 2 ˚C,

dehumidification 4 ˚C temperature required and 45 GPM (10368 LPH) flow .we selected

Plate heat exchanger have a higher overall heat transfer compare to shell and tube type heat

exchanger, lower initial cost, for a compact design space requirement is lower, and easy to

service compare to shell and tube heat exchanger and for recommended choice of compressor

30TR capacity choose reciprocating compressor. According to ASHARE 6.3.2.2.2 two

change over more efficient now day select two piping arrangement, parallel pumping and

chiller arrangement

Specification of chilled heat exchanger

Plate heat exchanger (stainless steel) IDMC made and 10.65 m2 heat transfer area

15 TR DX Chillers

51

Cold fluid Hot fluid

Flow rate 6200 LPH 11290 LPH

Inlet temperature -2˚C 6˚C

Outlet

temperature

-2˚C 2˚C

Hydrostat

pressure

9 kg/cm2 9 kg/cm2

Specification for condensing unit

Condensing unit made by Danfoss

15 TR capacity

Model HGM 160A06

Refrigerant = R22

High pressure =25 bar

Low pressure =8 bar

400V3 -50Hz

Specification of pump

Kirlosker brother made centrifugal pump

Head = 15 to 25 m

RPM = 2844

Flow= 3.1 lps

KW/HP=1.5/2.0, Bronze Impeller diameter =138 mm

Specification of measuring instrument

Pressure transmitter for pressure measuring

WIKA made 0-25 bar

Current 4 -20mA

RTD Temperature measuring device

PT 100 Yokogawa

0˚C to 100˚C

Flow switch to measure water flow

FM4WP Mukund electrical

Max temperature 150˚C

Max pressure 11 Kg/cm2, nominal diameter 50mm, Normal flow 170

52

CHAPTER 6: TEST ROOM LAYOUT

Testing room for bulk milk cooler is to test at different ambient temperature and maintain

ambient temperature .In these arrangement chillers arrange so that heating and cooling room.

As per ISO 1983:5708 bulk milk cooler company work on that basis we required 15 ˚ to 50˚

with stability of 0.2˚c around the surface of bulk milk cooler.

6.1 COOLING PROCESS:

In the cooling arrangement used direct expansion chiller (plate heat exchanger) by company

made. cooling system comprise vapor compression system evaporator , condensing unit

(receiver , compressor , condenser , expansion valve ) and their capacity on the basis of

calculation 30TR .In two pipe arrangement use two PHE chiller and for one PHE used two

condensing unit so there are two PHE chillier 15 TR and four condensing unit . We used two

centrifugal pumps for water circulation 3.13 l/s capacity .Pump suck water from sump

500liter syntax tank and two PHE outlet, discharge water goes to air handling unit and

recirculation through PHE. As same way refrigerant cycle comprise evaporator (PHE),

receiver, compressor, condenser, expansion valve, solenoid valve. R22 refrigerant extract

heat from water and cool water.

6.2 HEATING PROCESS:

In heating process of room used solar water heating system 300 liter and boiler 2 kg steam /

hr capacity company available unit circulate water from solar heating or boiler to hot tank

arrangement. At the time of heating application steam or warm water delivered with help of

hot water tank, pump suck hot water at the time suction of chiller water closed and open the

hot water valve and same during the time received from air handling unit PHE suction close

and hot water tank valve open .This system is made up to 50"c temperature condition.

6.3 BULK MILK COOLER TEST:

In the test room testing of bulk milk cooler by using water and cool the water 35˚C to

4˚C .System also comprise one pipe connection for bulk milk cooler set 35˚C hot water

temperature and fill up water according requirement after completion of test water back to

cold water tank.

53

Figure 6.1: Test Room Layout

6.4 BILL OF QUANTITIES:

54

Condensing Unit Qty

CDU Model - HGM 160 / Danfoss with controls 4

MS Stand for CDU 1

Copper piping 1 lot

Cabling 1 lot

Installation material 1 lot

Chilled water pump

45 GPM at 25 MWC, monoblock/bronze impeller 2

Steel pipe Pipe 50 NB 1 lot

Nitrile Rubber insulation 1 lot

Ball Valve 6

Non Return Valve 17

Strainer 1

3 way valve 2

Temperature Indicator 2

Pressure indicator 2

Flow switch 2

Temperature sensor 1

Expansion tank 1000 liters (syntax tank) 1


AHU

Ceiling suspended cooler 2

13 TR / 33000 CMH

De-super heater 1

Solar water heating system 1


Automation

Scada 1

Pressure transmitter 20

Temperature transmitter 34


Electrical Panel

55

MCC 1

Servo voltage stabilizer 50 KVA 1

Lighting 1 lot

Cabling 1 lot


PHE Chiller

15 TR DX PHE/R22 - SW 40 2


PUF Panel

PCGI 0.63mm PUF 40kg/m3 1 lot


Sliding Door

Sliding Door - 4.3m (w) x 3.2m (h) 1


Labour Work

AHU 1 lot

Door 1 lot

PUF Panel 1 lot

SCADA 1 lot

Cabling 1 lot

Water Piping 1 lot

CDU 1 lot

Total cost 42,00 ,000

Table 6.1 - Bill of Material

56

CHAPTER 7: THERMAL PERFORMANCE OF CHILLER

HEAT EXCHANGER

7.1 HEAT TRANSFER AND PRESSURE DROP CALCULATION:

The designed for gasketed –plate heat exchanger is highly specialized in nature considering

the variety of designs available for the plate and arrangements that may possibly sits various

duties. Manufacture has developed their own design procedure applicable to the exchangers

that they market. Here IDMC LIMITED made own plate heat exchanger for various

application fluids exchanges. For this company used plate data that mentioned below table

from standard plate data we select the no of plate and calculate the no of plates required for

given heat duty required and analyze heat transfer and pressure drop calculation as per

requirement of flows and refrigerant check the heat transfer and pressure drop within

acceptable limit or not. There is a parallel flow heat exchanger and data from required design.

Data sheet for Plate heat exchanger:

Items Hot Fluid Cold Fluid

Fluids Cooling water R22

Flow rates (kg/s) 3.13 1.72

Temperature in (0C) 6 -2

Temperature out (0C) 2 -2

Total fouling resistance (m2K/W) 0.000086 0.000044

Specific heat (J/kg.K) 4178 1.171X103

Viscosity (N.s/m2) 7.66X10-4 2.67X10-4

Thermal conductivity (W/m.K) 0.617 0.0977

Density (kg/m3) 995 1.285X103

Table 7.1 – Plate Heat Exchanger Data Sheet [B7]

57

The Construction Data for Proposed Plate Heat Exchange:

Plate Material SS316

Plate thickness, t (mm) 0.6

Chevron angle , β(degree) 60

Total number of plates, Nt 26

Enlargement factor, Φ 1.36

No of passes, Np One pass/one pass

Port diameter, Dp(mm) 100

Pack length, Lc(mm) 8.2

Vertical port distance , LV(mm) 1055

Horizontal port distance, Lh(mm) 225

Thermal conductivity (w/m.K) 16.5

Table 7.2 – Construction Data for Plate Heat Exchanger

Figure 7.1: Dimension View of Plate Heat Exchanger [B7]

7.2 STEPWISE PERFORMANCE ANALYSIS:

58

7.2.1 Required Heat Duties:

For a given application of heat exchanger required a cool water dehumidification temperature

and apparatus dew point. Here for capacity of bulk milk cooler required chiller water flow

rate 3.13l/s , cool water at apparatus dew point and required dehumidification so that from

heat capacity equation required heat exchanger duty for temperature 6˚C to 2˚C with specific

heat of water assume city water 4178J/kg K.

7.2.2 Sizing of Heat Exchanger:

The temperature difference for parallel flow heat exchanger at inlet and outlet is determined

by temperature difference of two fluids at inlet and outlet.

The effective number of plates is total no of plate subtract two plate for use holding heat

exchanger.

The effective flow length between the vertical ports is

Plate pitch can be determined by total pack length of heat exchanger divided no of plates

Mean channel flow gap for one plate can be determined by plate pitch subtract by thickness

of plate

59

The one Channel flow area is multiplication of width of plate and mean channel flow gap

Single Plate heat transfer area is determined by effective area of one plate that given by plate

manufacturer divided by effective no of plate

The projected area A1p is determined by

The enlargement factor specified by manufacturer but it can be verified by single plate area to

projected area of plate

The Channel hydraulic/equivalent diameter is determined by

The number of Channel per pass is

60

7.2.3 Heat Transfer Analysis:

Mass flow rate per channel for cold fluid total mass flow rate for cold fluid for maximum

flow rate of cooling water divided by no of channel per pass of particular cooling fluid

Mass velocity Gch

The hot fluid Reynolds number

Flow rate per channel for cold fluid

Mass velocity Gcc

Reynolds Number for cold fluid

61

The hot fluid convective heat transfer coefficient hh can be determined using Nusselt number

correlation suggest McAdams for Laminar flow 2*103<Re<1*106. Nusset number based on

hydraulic diameter of plate that convective heat transfer to conduction heat transfer

The Cold fluid heat transfer coefficient hc can be determined by.

For clean overall heat transfer UC determined by

The fouled overall heat transfer

The corresponding cleanliness factor is

The actual heat duties for clean and fouled condition can be determined by

62

Actual heat transfer given by

Percentage of over surface design

7.2.4 Pressure Drop Analysis:

The fluid friction co-efficient for hot and cold fluid determined by

The frictional pressure drop from hot & cold streams

The Pressure drop in port is calculated by

63

Total pressure drop can be determined by summation of friction and port pressure drop

Hot fluid side pressure drop

Cold fluid side pressure drop

As per calculation of heat transfer and pressure drop heat exchanger is sufficient for chiller

plant to achieve an ambient condition in bulk milk cooler testing laboratory and also 21%

over surface design allow due to cleaning of plate which is acceptable.

64

7.3 DATA ANALYSIS FOR HEAT TRANSFER WITH DIFFERENT CHILLER

FLOW RATES:

Chiller flow

rates(l/s)

Required heat duties

Q(Watt)

Actual heat capacity

Qact(Watt)

1.0 16748 67072

1.5 25122 70800

2.0 33496 73154

2.5 41780 74700

3.0 55436 76500

3.5 58618 76800

Table 7.3 – Chiller Heat Transfer Analysis

7.3.1 Heat Transfer Trends for Chiller Mass Flow Rates:

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

1 2 3 4 5 6

Chiller flow (l/s)

Hea

t ex

chan

ge

(Wat

t) Chiller flow

Required heatduty

Actual heatcapacity

Figure 7.2: Heat Transfer Trends for Chiller Flow Rate

CHAPTER 8: BULK MILK COOLER TEST

8.1 10 KL CLOSED TYPE BULK MILK COOLER TEST:

Standard cooling capacity for 10kl bulk milk cooler using two condensing unit hermetic type

by Danfoss made 28.64 KW capacities each.

65

Figure 8.1: 10KL Bulk Milk Cooler Set Up

8.1.1 Room Temperature and Chiller Test:

66

Figure 8.2: Chiller Arrangement

Time

(min)

Chiller 1 Flow

rate GPM (l/s)

Chiller 2 Flow

rate GPM (l/s)

Supply

temperature

(˚C)

Average room

temperature (˚C)

4:00 39.79(2.507) 39.43(2.485) 7.50 10.30

4:15 39.81(2.508) 39.57(2.493) 5.48 10.21

4:30 39.76(2.505) 39.62(2.497) 5.46 10.13

4:45 39.73(2.503) 39.64(2.498) 5.47 10.30

5:00 39.82(2.509) 39.55(2.492) 5.44 10.20

5:15 39.77(2.506) 39.51(2.490) 5.49 10.16

5:30 39.79(2.507) 39.56(2.493) 5.41 10.29

5:45 39.76(2.505) 39.60(2.495) 5.39 10.24

6:00 39.80(2.508) 39.58(2.494) 5.42 10.18

6:15 39.75(2.505) 39.56(2.493) 5.40 10.15

6:30 39.73(2.503) 39.52(2.490) 5.38 10.10

Table 8.1 - Chiller and Room Temperature Test for 10KL BMC

8.1.2 Bulk Milk Cooler Test:

67

Time

(min)

Suction

pressure

(Bar)

Discharge

pressure

(Bar)

Evaporator out

temperature

(˚C)

Liquid line

temperature

(˚C)

Water

temperature

(˚C)

4:00 4.86 19.24 33.31 43 35

4:15 5.00 20.24 32.53 48 31.2

4:30 5.16 21.00 29.81 52 27.6

4:45 5.06 21.33 27.01 51 24.4

5:00 5.20 21.32 24.21 50 21

5:15 5.13 21.20 21.28 51 17.7

5:30 4.78 20.68 16.21 52 14.6

5:45 4.56 20.44 10.26 50 11.6

6:00 4.41 19.89 5.01 47 8.9

6:15 3.99 18.95 1.12 41 6.3

6:30 3.59 18.26 0.5 41 3.9

Table 8.2 - 10KL Bulk Milk Cooler Test

8.1.3 Calculation for Heat Removed from Condenser:

(1) At 4:00 PM

Suction Pressure P0 =4.86 bar,

Discharge Pressure P1 = 19.24 bar,

Evaporator out temperature Te= 33.31 ˚C

Liquid line temperature T3=43˚C

Using this data from p - h chart getting Enthalpy values

h1 =274 kJ/kg, h2=335 kJ/kg, h4=103 kJ/kg= h3,

Q = m*(h1- h4) kJ/s

28.67=m*(274-103)

m = 0.167 kg/s

So heat rejected from compressor

Qrej = m*(h2- h3) kJ/s

= 0.167*(335-103)

=38.74 kW

8.1.4 As Per Calculation at 4:00 PM Heat Removed from Condenser Same

Procedure for Another Time .Total Room Load the Time of Testing and Required 68

Chiller Flow Rates:

Time (min) Product load TR Total load

TR

Flow GPM(L/s)

(TR*3)

4:00 22.05 26.87 80.64(5.08)

4:15 21.21 26.00 78.00(4.91)

4:30 21.47 26.28 78.84(4.97)

4:45 21.85 26.71 80.13(5.05)

5:00 21.12 25.90 77.70(4.90)

5:15 21.26 25.19 75.57(4.76)

5:30 22.75 27.70 83.10(5.24)

5:45 22.56 27.49 82.47(5.20)

6:00 21.26 26.06 78.18(4.93)

6:15 20.77 25.45 76.35(4.81)

6:30 21.28 26.09 78.27(4.93)

Table 8.3 - Total Room Load for 10KL BMC

8.2 CLOSED TYPE BULK MILK COOLER TEST:

69

5KL bulk milk cooler test at outside ambient temperature 39˚C and inside design temperature

10˚C. Bulk milk cooler installed with two hermetic compressors with capacity of 14.66 KW

each unit as shown in below.

Figure 8.3: 5KL Bulk Milk Cooler Set Up

70

8.2.1 Room Temperature and Chiller Test:

Time

(min)

Chiller 1 Flow

rate GPM (L/s)

Supply

temperature

(˚C)

Average room

temperature (˚C)

2:00 50.79(3.201) 10.02 10.30

2:15 51.29(3.232) 8.29 10.21

2:30 51.43 (3.241) 6.35 10.13

2:45 51.39(3.238) 5.25 10.30

3:00 51.36(3.236) 5.21 10.20

3:15 51.42(3.240) 5.18 10.16

3:30 51.34(3.235) 5.05 10.29

3:45 51.37(3.237) 4.87 10.24

4:00 51.40(3.239) 4.63 10.18

4:15 51.42(3.240) 4.57 10.15

4:30 51.45(3.242) 4.39 10.10

Table 8.4 - Chiller and Room Test for 5KL BMC

71

8.2.2 5KL Bulk Milk Cooler Test:

Time

(min)

Suction

pressure

(Bar)

Discharge

pressure

(Bar)

Evaporator

out

temperature

(˚C)

Liquid line

temperature

(˚C)

Water

temperature

(˚C)

2:00 6.21 20.34 23.1 46.0 35.0

2:15 6.20 19.65 19.0 45.1 30.7

2:30 6.07 18.62 16.2 44.2 26.9

2:45 5.52 18.96 13.8 43.4 23.5

3:00 5.17 18.61 09.4 43.1 20.2

3:15 4.83 17.93 07.2 42.8 17.0

3:30 4.48 17.58 05.4 42.0 14.0

3:45 3.79 16.21 04.0 40.7 11.5

4:00 3.45 15.86 02.2 40.2 9.1

4:15 3.10 15.52 01.5 39.0 6.5

4:30 3.08 15.23 0.50 38.6 4.1


8.2.3 Calculation for Heat Removed from Condenser:

(1) At 2:00 PM




Liquid line temperature T3 =46 ˚C



Q = m*(h1- h4) kJ/s

14.66=m*(271-110)

m = 0.091 kg/s



= 0.091*(319-110)

=19.031 kW72

8.2.4 As Per Calculation of 2:00 PM Same Calculation for Another Time. Total

Room Load at the Time of Testing and Required Chiller Flow Rates:

Time (min) Product load

TR

Total load

TR

Flow GPM(L/s)

(TR*3)

2:00 10.82 14.69 44.07(2.78)

2:15 10.64 14.50 43.50(2.74)

2:30 10.33 14.15 42.45(2.67)

2:45 10.32 14.14 42.42(2.67)

3:00 10.21 14.02 42.06(2.65)

3:15 10.48 14.32 42.49(2.71)

3:30 10.55 14.40 43.20(2.72)

3:45 10.86 14.73 44.19(2.78)

4:00 11.27 15.19 45.57(2.87)

4:15 11.26 15.18 45.54(2.86)

4:30 11.26 15.18 45.54(2.86)

Table 8.6 - Total Room load for 5KL BMC

8.3 2KL CLOSED TYPE BULK MILK COOLER TEST:

73

For 2KL bulk milk cooler tested under average outside ambient temperature

40˚C and inside ambient 38˚C. Bulk milk cooler installed with two hermetic type

compressors capacity of 6.23 KW of each unit.

8.3.1 Room Temperature and Chiller Result:

Time

(min)

Chiller Flow

rate GPM (l/s)

Supply

temperature

(˚C)

Average room

temperature (˚C)

03:55 1.12 21.00 38.34

04:10 1.15 18.25 38.21

04:25 1.13 15.24 38.24

04:40 1.20 14.20 38.17

04:55 1.18 13.25 38.24

05:10 1.14 11.78 38.31

05:25 1.12 11.25 38.18

05:40 1.16 10.49 38.16

05:55 1.19 10.25 38.22

06:10 1.18 09.80 38.28

06:25 1.20 09.50 38.15

06:40 1.17 09.10 38.02

Table 8.7 - Chiller and Room Test for 2KL BMC

8.3.2 2KL Bulk Milk Cooler Test:

74

Suction

pressure

(Bar)

Discharge

pressure

(Bar)

Evaporator

out

temperature

(˚C)

Liquid line

temperature

(˚C)

Water

temperature

(˚C)

03:55 18.97 32.4 47.7 35.0

04:10 18.97 25.0 48.0 30.9

04:25 18.62 19.4 46.4 26.9

04:40 17.93 13.6 44.9 23.5

04:55 17.24 10.3 43.8 20.4

05:10 17.24 8.0 43.0 17.4

05:25 16.55 6.2 41.8 14.7

05:40 15.72 5.4 40.9 12.5

05:55 15.52 3.8 39.7 10.4

06:10 15.17 2.3 38.9 8.4

06:25 15.17 1.5 37.9 6.4

06:40 14.83 0.4 37.8 4.0


8.3.3 Calculations for Heat Removed from Condenser:

(1) At 3:55 PM




Liquid line temperature T3 =47.7˚C



Q = m*(h1- h4) kJ/s

6.23=m*(281-111)

m = 0.037 kg/s



= 0.037*(318-111)

=7.59 kW75

8.3.4 Total Room Load at the Time of Testing and Required Chiller Flow Rates:

Time (min) Product

load TR

Total load

TR

Flow GPM(L/s)

(TR*3)

07:55 4.31 5.391 16.17(1.02)

08:10 4.31 5.391 16.17(1.02)

08:25 4.83 5.964 17.89(1.13)

08:40 4.31 5.391 16.17(1.02)

08:55 4.36 5.446 16.34(1.03)

09:10 4.42 5.512 16.54(1.04)

09:25 4.54 5.644 16.93(1.07)

09:40 4.67 5.787 17.36(1.09)

09:55 4.64 5.754 17.26(1.08)

10:10 4.63 5.743 17.23(1.08)

10:25 4.70 5.820 17.46(1.10)

10:40 4.70 5.820 17.46(1.10)

Table 8.9 - Total Room Load for 2KL BMC

76

CHAPTER 9: RESULT AND DISCUSSION

9.1 For 10 KL BULK MILK COOLER:

10KL bulk milk cooler testing at outside temperature 39˚C and inside temperature 10˚C. We

obtained almost uniform temperature as per ISO 5708:1983 mentioned. For room average

temperature installed six number of RTD sensor use three for left wall and three for right wall

and equally spaced from air handling unit . For 10KL and 10˚C inside temperature three way

controls valve is fully open and achieve full chiller flow rate that maintain room temperature.

9.1.1 Comparison of Chiller Flow Rate and Required Flow Rate:

Time

(min)

Predict Flow

GPM(L/s)

(TR*3)

Chiller 1 Flow rate

GPM (L/s)

Chiller 2 Flow rate

GPM (L/s)

4:00 80.64(5.08) 39.79(2.507) 39.43(2.485)

4:15 78.00(4.91) 39.81(2.508) 39.57(2.493)

4:30 78.84(4.97) 39.76(2.505) 39.62(2.497)

4:45 80.13(5.05) 39.73(2.503) 39.64(2.498)

5:00 77.70(4.90) 39.82(2.509) 39.55(2.492)

5:15 75.57(4.76) 39.77(2.506) 39.51(2.490)

5:30 83.10(5.24) 39.79(2.507) 39.56(2.493)

5:45 82.47(5.20) 39.76(2.505) 39.60(2.495)

6:00 78.18(4.93) 39.80(2.508) 39.58(2.494)

6:15 76.35(4.81) 39.75(2.505) 39.56(2.493)

6:30 78.27(4.93) 39.73(2.503) 39.52(2.490)

Table 9.1 - Compare chiller flow rate for 10KL BMC

77

9.1.2 Average Room Temperature Trend:

Figure 9.1: Average Room Temperature Trend for 10KL BMC

9.1.3 Predictable and Experimental Chiller Flow Trend:

4.2

4.4

4.6

4.8

5

5.2

5.4

4:00

4:30

5:00

5:30

6:00

6:30

Time (min)

Flo

w r

ate

(l/s

)

Predict flow

Experimentflow

Figure 9.2: Chiller Flow Trend for 10KL

9.2 For 5KL BULK MILK COOLER:

78

For 5KL bulk milk cooler test at outside room average temperature 39˚C and inside

temperature 10˚C we obtained uniform room temperature at the time of test three way control

valve 70 % open and flow rate is decrease that meet the required chiller water flow and for

this only one.

9.2.1 Comparison of Chiller Flow Rate and Required Flow

Rate:

Time (min) Predict Flow

GPM(L/s) (TR*3)

Chiller 1 Flow

rate GPM (L/s)

2:00 44.07(2.78) 50.79(3.201)

2:15 43.50(2.74) 51.29(3.232)

2:30 42.45(2.67) 51.43 (3.241)

2:45 42.42(2.67) 51.39(3.238)

3:00 42.06(2.65) 51.36(3.236)

3:15 42.49(2.71) 51.42(3.240)

3:30 43.20(2.72) 51.34(3.235)

3:45 44.19(2.78) 51.37(3.237)

4:00 45.57(2.87) 51.40(3.239)

4:15 45.54(2.86) 51.42(3.240)

4:30 45.54(2.86) 51.45(3.242)

Table 9.2 - Compare Chiller Flow Rate for 5KL BMC

79


Figure 9.3: Average Room Temperature Trend for 5KL

9.2.3 Prediction and Experimental Chiller Trend

Figure 9.4: Chiller Flow Trend for 5KL

80

9.3 FOR 2KL BULK MILK COOLER:

For a 2kl bulk milk cooler test outside temperature 40˚C and inside temperature 38˚C for this

condition 35% three way control valve open and achieve temperature and flow rate as per

requirement of test.

9.3.1 Comparison of Chiller Flow Rate and Required Flow

Rate:

Time (min) Predict Flow GPM(L/s)

(TR*3)

Chiller Flow rate

GPM (L/s)

03:55 16.17(1.02) 1.12

04:10 16.17(1.02) 1.15

04:25 17.89(1.13) 1.13

04:40 16.17(1.02) 1.20

04:55 16.34(1.03) 1.18

05:10 16.54(1.04) 1.14

05:25 16.93(1.07) 1.12

05:40 17.36(1.09) 1.16

05:55 17.26(1.08) 1.19

06:10 17.23(1.08) 1.18

06:25 17.46(1.10) 1.20

06:40 17.46(1.10) 1.17

Table 9.3 - Compare Chiller Flow Rate for 2KL BMC

81


Figure 9.5: Average Room Temperature Trend for 2KL BMC

9.3.3 Prediction and Experimental Chiller Trend:

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

Time(min)

Ch

ille

r fl

ow

(l/s

)

Prediction flow

Experimentflow

Figure 9.6: Chiller Flow Trend for 2KL BMC

82

CHAPTER 10: CONCLUSION

From designing and experimental point of conclude that for any air condition system

complete information require where it is installed after getting primary information

calculation of heat load is important based on required application that include all heat source

.Based on heat load calculation find chiller flow required to achieve temperature and

selection of cooling equipment as per heat load .In this case different capacity of bulk milk

cooler test so that equipment load vary set the control valve system as per predict load for

different capacity of bulk milk cooler and weather data for summer and winter condition.

From experiment view we tested different types of bulk milk cooler chiller heat exchanger is

enough to maintain ambient condition as we set three way control valve according design

heat load calculation so that water flow rate change for different types of bulk milk cooler

and outside design temperature as we calculated that achieve uniform temperature as

customer said where bulk milk cooler will use. Achieve uniform ambient temperature as

mentioned ISO 5708:1983 bulk milk cooler section and dispatch to customer as they told

ambient condition.

83

REFERENCES

PAPERS:

1. Alka Bani Agrawal, R.K. Dave and Vipin Shrivastava, “Replacing harmful refrigerant

R22 in bulk milk cooler”, Indian Journal of Science and Technology. Vol.2 No. 9 (Sep

2009), ISSN: 0974- 6846

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in industrial facility”, Universidad Politecnica de C artegena, Spain,

[email protected]

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BOOKS:

1. ASHRAE Fundamentals Handbook ASHRAE. Atlanta, 2000

2. ASHRAE HVAC Systems and Equipment Handbook ASHRAE. Atlanta, 2001

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7. R. K. Shah, Fundamental of Heat Exchanger Design, John Wiley & Sons, 2003

8. R.K. Rajput, Refrigeration and Air Conditioning, 1st Edition, S.K.Kataria and Sons, 2004

9. Ross Montgomery, Fundamental HVAC Control System, 2nd Edition, Elsevier, 2003

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APPENDIX -A

Friction Factor and Nusset Number Correlation for Gasket-Plate Heat Exchanger with Chevron Plates [B7]:

1. Tait etal, β=60˚ chevron plates:

f =12.065Re-0.74 10< Re<80

=0.3323 Re-0.042 1450< Re<11460

Nu=0.2 Re0.75 Pr0.4 10< Re<720

=0.248Re0.7 Pr0.4 1450< Re<11460

2. Muley and Maglik, β=60˚ chevron plates:

f =51.5/Re Re<16

=17.0Re-0.6 16< Re<100

=2.48Re-0.2 Re>800

Nu=0.572 Re0.5 Pr1/3 20< Re<210

=0.1090Re0.78 Pr1/3 Re>800

3. Muley and Maglik, Mixed chevron plate with β=30˚ & 45˚ angle:

f= {(40.32/ Re) 5+ (8.21 Re-0.5)5}0.2 2< Re<200

= 1.27 Re-0.15 Re>1000

Nu=0.471 Re0.5 Pr1/3 20< Re<400

=0.10Re0.78 Pr1/3 Re>1000

4. McAdam Correlation for 2*103< Re<1*106 for β=60˚ chevron angle:

f= 1.441/( Re)0.206

Nu=0.3(Re) 0.663(Pr) 1/3(µb/µw)0.17

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Documents

Raj Thesis 2003